changeset 4750:71fd601907dc

4360113: Evict nmethods when code cache gets full Summary: Speculatively unload the oldest nmethods when code cache gets full. Reviewed-by: never, kvn Contributed-by: eric.caspole@amd.com
author kvn
date Fri, 29 Jan 2010 09:27:22 -0800
parents f26b30116e3a
children 9418f690831d
files hotspot/src/share/vm/ci/ciEnv.cpp hotspot/src/share/vm/code/codeCache.cpp hotspot/src/share/vm/code/codeCache.hpp hotspot/src/share/vm/code/nmethod.cpp hotspot/src/share/vm/code/nmethod.hpp hotspot/src/share/vm/compiler/compileBroker.cpp hotspot/src/share/vm/compiler/compileBroker.hpp hotspot/src/share/vm/includeDB_compiler2 hotspot/src/share/vm/includeDB_core hotspot/src/share/vm/oops/methodOop.cpp hotspot/src/share/vm/oops/methodOop.hpp hotspot/src/share/vm/opto/output.cpp hotspot/src/share/vm/runtime/compilationPolicy.cpp hotspot/src/share/vm/runtime/globals.hpp hotspot/src/share/vm/runtime/sharedRuntime.cpp hotspot/src/share/vm/runtime/sweeper.cpp hotspot/src/share/vm/runtime/sweeper.hpp hotspot/src/share/vm/runtime/vm_operations.cpp hotspot/src/share/vm/runtime/vm_operations.hpp
diffstat 19 files changed, 452 insertions(+), 76 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/src/share/vm/ci/ciEnv.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/ci/ciEnv.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -962,18 +962,10 @@
     if (nm == NULL) {
       // The CodeCache is full.  Print out warning and disable compilation.
       record_failure("code cache is full");
-      UseInterpreter = true;
-      if (UseCompiler || AlwaysCompileLoopMethods ) {
-#ifndef PRODUCT
-        warning("CodeCache is full. Compiler has been disabled");
-        if (CompileTheWorld || ExitOnFullCodeCache) {
-          before_exit(JavaThread::current());
-          exit_globals(); // will delete tty
-          vm_direct_exit(CompileTheWorld ? 0 : 1);
-        }
-#endif
-        UseCompiler               = false;
-        AlwaysCompileLoopMethods  = false;
+      {
+        MutexUnlocker ml(Compile_lock);
+        MutexUnlocker locker(MethodCompileQueue_lock);
+        CompileBroker::handle_full_code_cache();
       }
     } else {
       NOT_PRODUCT(nm->set_has_debug_info(has_debug_info); )
--- a/hotspot/src/share/vm/code/codeCache.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/code/codeCache.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -96,6 +96,7 @@
 int CodeCache::_number_of_nmethods_with_dependencies = 0;
 bool CodeCache::_needs_cache_clean = false;
 nmethod* CodeCache::_scavenge_root_nmethods = NULL;
+nmethod* CodeCache::_saved_nmethods = NULL;
 
 
 CodeBlob* CodeCache::first() {
@@ -395,6 +396,85 @@
 }
 #endif //PRODUCT
 
+
+nmethod* CodeCache::find_and_remove_saved_code(methodOop m) {
+  MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+  nmethod* saved = _saved_nmethods;
+  nmethod* prev = NULL;
+  while (saved != NULL) {
+    if (saved->is_in_use() && saved->method() == m) {
+      if (prev != NULL) {
+        prev->set_saved_nmethod_link(saved->saved_nmethod_link());
+      } else {
+        _saved_nmethods = saved->saved_nmethod_link();
+      }
+      assert(saved->is_speculatively_disconnected(), "shouldn't call for other nmethods");
+      saved->set_speculatively_disconnected(false);
+      saved->set_saved_nmethod_link(NULL);
+      if (PrintMethodFlushing) {
+        saved->print_on(tty, " ### nmethod is reconnected");
+      }
+      if (LogCompilation && (xtty != NULL)) {
+        ttyLocker ttyl;
+        xtty->begin_elem("nmethod_reconnected compile_id='%3d'", saved->compile_id());
+        xtty->method(methodOop(m));
+        xtty->stamp();
+        xtty->end_elem();
+      }
+      return saved;
+    }
+    prev = saved;
+    saved = saved->saved_nmethod_link();
+  }
+  return NULL;
+}
+
+void CodeCache::remove_saved_code(nmethod* nm) {
+  MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+  assert(nm->is_speculatively_disconnected(), "shouldn't call for other nmethods");
+  nmethod* saved = _saved_nmethods;
+  nmethod* prev = NULL;
+  while (saved != NULL) {
+    if (saved == nm) {
+      if (prev != NULL) {
+        prev->set_saved_nmethod_link(saved->saved_nmethod_link());
+      } else {
+        _saved_nmethods = saved->saved_nmethod_link();
+      }
+      if (LogCompilation && (xtty != NULL)) {
+        ttyLocker ttyl;
+        xtty->begin_elem("nmethod_removed compile_id='%3d'", nm->compile_id());
+        xtty->stamp();
+        xtty->end_elem();
+      }
+      return;
+    }
+    prev = saved;
+    saved = saved->saved_nmethod_link();
+  }
+  ShouldNotReachHere();
+}
+
+void CodeCache::speculatively_disconnect(nmethod* nm) {
+  assert_locked_or_safepoint(CodeCache_lock);
+  assert(nm->is_in_use() && !nm->is_speculatively_disconnected(), "should only disconnect live nmethods");
+  nm->set_saved_nmethod_link(_saved_nmethods);
+  _saved_nmethods = nm;
+  if (PrintMethodFlushing) {
+    nm->print_on(tty, " ### nmethod is speculatively disconnected");
+  }
+  if (LogCompilation && (xtty != NULL)) {
+    ttyLocker ttyl;
+    xtty->begin_elem("nmethod_disconnected compile_id='%3d'", nm->compile_id());
+    xtty->method(methodOop(nm->method()));
+    xtty->stamp();
+    xtty->end_elem();
+  }
+  nm->method()->clear_code();
+  nm->set_speculatively_disconnected(true);
+}
+
+
 void CodeCache::gc_prologue() {
   assert(!nmethod::oops_do_marking_is_active(), "oops_do_marking_epilogue must be called");
 }
--- a/hotspot/src/share/vm/code/codeCache.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/code/codeCache.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -46,6 +46,7 @@
   static int _number_of_nmethods_with_dependencies;
   static bool _needs_cache_clean;
   static nmethod* _scavenge_root_nmethods;  // linked via nm->scavenge_root_link()
+  static nmethod* _saved_nmethods;          // linked via nm->saved_nmethod_look()
 
   static void verify_if_often() PRODUCT_RETURN;
 
@@ -141,11 +142,16 @@
   static size_t  capacity()                      { return _heap->capacity(); }
   static size_t  max_capacity()                  { return _heap->max_capacity(); }
   static size_t  unallocated_capacity()          { return _heap->unallocated_capacity(); }
+  static bool    needs_flushing()                { return unallocated_capacity() < CodeCacheFlushingMinimumFreeSpace; }
 
   static bool needs_cache_clean()                { return _needs_cache_clean; }
   static void set_needs_cache_clean(bool v)      { _needs_cache_clean = v;    }
   static void clear_inline_caches();             // clear all inline caches
 
+  static nmethod* find_and_remove_saved_code(methodOop m);
+  static void remove_saved_code(nmethod* nm);
+  static void speculatively_disconnect(nmethod* nm);
+
   // Deoptimization
   static int  mark_for_deoptimization(DepChange& changes);
 #ifdef HOTSWAP
--- a/hotspot/src/share/vm/code/nmethod.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/code/nmethod.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -587,6 +587,7 @@
     _osr_link                = NULL;
     _scavenge_root_link      = NULL;
     _scavenge_root_state     = 0;
+    _saved_nmethod_link      = NULL;
     _compiler                = NULL;
     // We have no exception handler or deopt handler make the
     // values something that will never match a pc like the nmethod vtable entry
@@ -1033,7 +1034,7 @@
         if( cb != NULL && cb->is_nmethod() ) {
           nmethod* nm = (nmethod*)cb;
           // Clean inline caches pointing to both zombie and not_entrant methods
-          if (!nm->is_in_use()) ic->set_to_clean();
+          if (!nm->is_in_use() || (nm->method()->code() != nm)) ic->set_to_clean();
         }
         break;
       }
@@ -1043,7 +1044,7 @@
         if( cb != NULL && cb->is_nmethod() ) {
           nmethod* nm = (nmethod*)cb;
           // Clean inline caches pointing to both zombie and not_entrant methods
-          if (!nm->is_in_use()) csc->set_to_clean();
+          if (!nm->is_in_use() || (nm->method()->code() != nm)) csc->set_to_clean();
         }
         break;
       }
@@ -1312,7 +1313,8 @@
   // completely deallocate this method
   EventMark m("flushing nmethod " INTPTR_FORMAT " %s", this, "");
   if (PrintMethodFlushing) {
-    tty->print_cr("*flushing nmethod " INTPTR_FORMAT ". Live blobs: %d", this, CodeCache::nof_blobs());
+    tty->print_cr("*flushing nmethod %3d/" INTPTR_FORMAT ". Live blobs:" UINT32_FORMAT "/Free CodeCache:" SIZE_FORMAT "Kb",
+        _compile_id, this, CodeCache::nof_blobs(), CodeCache::unallocated_capacity()/1024);
   }
 
   // We need to deallocate any ExceptionCache data.
@@ -1330,6 +1332,10 @@
     CodeCache::drop_scavenge_root_nmethod(this);
   }
 
+  if (is_speculatively_disconnected()) {
+    CodeCache::remove_saved_code(this);
+  }
+
   ((CodeBlob*)(this))->flush();
 
   CodeCache::free(this);
--- a/hotspot/src/share/vm/code/nmethod.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/code/nmethod.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -95,6 +95,8 @@
   unsigned int has_unsafe_access:1;          // May fault due to unsafe access.
   unsigned int has_method_handle_invokes:1;  // Has this method MethodHandle invokes?
 
+  unsigned int speculatively_disconnected:1; // Marked for potential unload
+
   void clear();
 };
 
@@ -137,6 +139,7 @@
   // To support simple linked-list chaining of nmethods:
   nmethod*  _osr_link;         // from instanceKlass::osr_nmethods_head
   nmethod*  _scavenge_root_link; // from CodeCache::scavenge_root_nmethods
+  nmethod*  _saved_nmethod_link; // from CodeCache::speculatively_disconnect
 
   static nmethod* volatile _oops_do_mark_nmethods;
   nmethod*        volatile _oops_do_mark_link;
@@ -413,6 +416,9 @@
   bool  has_method_handle_invokes() const         { return flags.has_method_handle_invokes; }
   void  set_has_method_handle_invokes(bool z)     { flags.has_method_handle_invokes = z; }
 
+  bool  is_speculatively_disconnected() const     { return flags.speculatively_disconnected; }
+  void  set_speculatively_disconnected(bool z)     { flags.speculatively_disconnected = z; }
+
   int   level() const                             { return flags.level; }
   void  set_level(int newLevel)                   { check_safepoint(); flags.level = newLevel; }
 
@@ -437,6 +443,9 @@
   nmethod* scavenge_root_link() const                  { return _scavenge_root_link; }
   void     set_scavenge_root_link(nmethod *n)          { _scavenge_root_link = n; }
 
+  nmethod* saved_nmethod_link() const                  { return _saved_nmethod_link; }
+  void     set_saved_nmethod_link(nmethod *n)          { _saved_nmethod_link = n; }
+
  public:
 
   // Sweeper support
--- a/hotspot/src/share/vm/compiler/compileBroker.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/compiler/compileBroker.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -69,6 +69,7 @@
 
 bool CompileBroker::_initialized = false;
 volatile bool CompileBroker::_should_block = false;
+volatile jint CompileBroker::_should_compile_new_jobs = run_compilation;
 
 // The installed compiler(s)
 AbstractCompiler* CompileBroker::_compilers[2];
@@ -986,6 +987,13 @@
       return method_code;
     }
     if (method->is_not_compilable(comp_level)) return NULL;
+
+    nmethod* saved = CodeCache::find_and_remove_saved_code(method());
+    if (saved != NULL) {
+      method->set_code(method, saved);
+      return saved;
+    }
+
   } else {
     // osr compilation
 #ifndef TIERED
@@ -1037,6 +1045,14 @@
     method->jmethod_id();
   }
 
+  // If the compiler is shut off due to code cache flushing or otherwise,
+  // fail out now so blocking compiles dont hang the java thread
+  if (!should_compile_new_jobs() || (UseCodeCacheFlushing && CodeCache::needs_flushing())) {
+    method->invocation_counter()->decay();
+    method->backedge_counter()->decay();
+    return NULL;
+  }
+
   // do the compilation
   if (method->is_native()) {
     if (!PreferInterpreterNativeStubs) {
@@ -1325,26 +1341,13 @@
     {
       // We need this HandleMark to avoid leaking VM handles.
       HandleMark hm(thread);
+
       if (CodeCache::unallocated_capacity() < CodeCacheMinimumFreeSpace) {
-        // The CodeCache is full.  Print out warning and disable compilation.
-        UseInterpreter = true;
-        if (UseCompiler || AlwaysCompileLoopMethods ) {
-          if (log != NULL) {
-            log->begin_elem("code_cache_full");
-            log->stamp();
-            log->end_elem();
-          }
-#ifndef PRODUCT
-          warning("CodeCache is full. Compiler has been disabled");
-          if (CompileTheWorld || ExitOnFullCodeCache) {
-            before_exit(thread);
-            exit_globals(); // will delete tty
-            vm_direct_exit(CompileTheWorld ? 0 : 1);
-          }
-#endif
-          UseCompiler               = false;
-          AlwaysCompileLoopMethods  = false;
-        }
+        // the code cache is really full
+        handle_full_code_cache();
+      } else if (UseCodeCacheFlushing && CodeCache::needs_flushing()) {
+        // Attempt to start cleaning the code cache while there is still a little headroom
+        NMethodSweeper::handle_full_code_cache(false);
       }
 
       CompileTask* task = queue->get();
@@ -1369,7 +1372,7 @@
       // Never compile a method if breakpoints are present in it
       if (method()->number_of_breakpoints() == 0) {
         // Compile the method.
-        if (UseCompiler || AlwaysCompileLoopMethods) {
+        if ((UseCompiler || AlwaysCompileLoopMethods) && CompileBroker::should_compile_new_jobs()) {
 #ifdef COMPILER1
           // Allow repeating compilations for the purpose of benchmarking
           // compile speed. This is not useful for customers.
@@ -1614,6 +1617,38 @@
 
 
 // ------------------------------------------------------------------
+// CompileBroker::handle_full_code_cache
+//
+// The CodeCache is full.  Print out warning and disable compilation or
+// try code cache cleaning so compilation can continue later.
+void CompileBroker::handle_full_code_cache() {
+  UseInterpreter = true;
+  if (UseCompiler || AlwaysCompileLoopMethods ) {
+    CompilerThread* thread = CompilerThread::current();
+    CompileLog* log = thread->log();
+    if (log != NULL) {
+      log->begin_elem("code_cache_full");
+      log->stamp();
+      log->end_elem();
+    }
+  #ifndef PRODUCT
+    warning("CodeCache is full. Compiler has been disabled");
+    if (CompileTheWorld || ExitOnFullCodeCache) {
+      before_exit(JavaThread::current());
+      exit_globals(); // will delete tty
+      vm_direct_exit(CompileTheWorld ? 0 : 1);
+    }
+  #endif
+    if (UseCodeCacheFlushing) {
+      NMethodSweeper::handle_full_code_cache(true);
+    } else {
+      UseCompiler               = false;
+      AlwaysCompileLoopMethods  = false;
+    }
+  }
+}
+
+// ------------------------------------------------------------------
 // CompileBroker::set_last_compile
 //
 // Record this compilation for debugging purposes.
--- a/hotspot/src/share/vm/compiler/compileBroker.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/compiler/compileBroker.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -193,6 +193,9 @@
   static bool _initialized;
   static volatile bool _should_block;
 
+  // This flag can be used to stop compilation or turn it back on
+  static volatile jint _should_compile_new_jobs;
+
   // The installed compiler(s)
   static AbstractCompiler* _compilers[2];
 
@@ -319,6 +322,7 @@
 
   static void compiler_thread_loop();
 
+  static uint get_compilation_id() { return _compilation_id; }
   static bool is_idle();
 
   // Set _should_block.
@@ -328,6 +332,20 @@
   // Call this from the compiler at convenient points, to poll for _should_block.
   static void maybe_block();
 
+  enum {
+    // Flags for toggling compiler activity
+    stop_compilation = 0,
+    run_compilation  = 1
+  };
+
+  static bool should_compile_new_jobs() { return UseCompiler && (_should_compile_new_jobs == run_compilation); }
+  static bool set_should_compile_new_jobs(jint new_state) {
+    // Return success if the current caller set it
+    jint old = Atomic::cmpxchg(new_state, &_should_compile_new_jobs, 1-new_state);
+    return (old == (1-new_state));
+  }
+  static void handle_full_code_cache();
+
   // Return total compilation ticks
   static jlong total_compilation_ticks() {
     return _perf_total_compilation != NULL ? _perf_total_compilation->get_value() : 0;
--- a/hotspot/src/share/vm/includeDB_compiler2	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/includeDB_compiler2	Fri Jan 29 09:27:22 2010 -0800
@@ -775,6 +775,7 @@
 output.cpp                              assembler.inline.hpp
 output.cpp                              callnode.hpp
 output.cpp                              cfgnode.hpp
+output.cpp                              compileBroker.hpp
 output.cpp                              debugInfo.hpp
 output.cpp                              debugInfoRec.hpp
 output.cpp                              handles.inline.hpp
--- a/hotspot/src/share/vm/includeDB_core	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/includeDB_core	Fri Jan 29 09:27:22 2010 -0800
@@ -1032,6 +1032,7 @@
 codeCache.cpp                           oop.inline.hpp
 codeCache.cpp                           pcDesc.hpp
 codeCache.cpp                           resourceArea.hpp
+codeCache.cpp                           xmlstream.hpp
 
 codeCache.hpp                           allocation.hpp
 codeCache.hpp                           codeBlob.hpp
@@ -1120,6 +1121,7 @@
 compileBroker.cpp                       oop.inline.hpp
 compileBroker.cpp                       os.hpp
 compileBroker.cpp                       sharedRuntime.hpp
+compileBroker.cpp                       sweeper.hpp
 compileBroker.cpp                       systemDictionary.hpp
 compileBroker.cpp                       vmSymbols.hpp
 
@@ -3719,6 +3721,7 @@
 sharedRuntime.cpp                       abstractCompiler.hpp
 sharedRuntime.cpp                       arguments.hpp
 sharedRuntime.cpp                       biasedLocking.hpp
+sharedRuntime.cpp                       compileBroker.hpp
 sharedRuntime.cpp                       compiledIC.hpp
 sharedRuntime.cpp                       compilerOracle.hpp
 sharedRuntime.cpp                       copy.hpp
@@ -3973,6 +3976,7 @@
 
 sweeper.cpp                             atomic.hpp
 sweeper.cpp                             codeCache.hpp
+sweeper.cpp                             compileBroker.hpp
 sweeper.cpp                             events.hpp
 sweeper.cpp                             methodOop.hpp
 sweeper.cpp                             mutexLocker.hpp
@@ -3980,6 +3984,8 @@
 sweeper.cpp                             os.hpp
 sweeper.cpp                             resourceArea.hpp
 sweeper.cpp                             sweeper.hpp
+sweeper.cpp                             vm_operations.hpp
+sweeper.cpp                             xmlstream.hpp
 
 symbolKlass.cpp                         gcLocker.hpp
 symbolKlass.cpp                         handles.inline.hpp
@@ -4633,6 +4639,7 @@
 vm_operations.cpp                       interfaceSupport.hpp
 vm_operations.cpp                       isGCActiveMark.hpp
 vm_operations.cpp                       resourceArea.hpp
+vm_operations.cpp                       sweeper.hpp
 vm_operations.cpp                       threadService.hpp
 vm_operations.cpp                       thread_<os_family>.inline.hpp
 vm_operations.cpp                       vmSymbols.hpp
--- a/hotspot/src/share/vm/oops/methodOop.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/oops/methodOop.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -705,6 +705,16 @@
 // This function must not hit a safepoint!
 address methodOopDesc::verified_code_entry() {
   debug_only(No_Safepoint_Verifier nsv;)
+  nmethod *code = (nmethod *)OrderAccess::load_ptr_acquire(&_code);
+  if (code == NULL && UseCodeCacheFlushing) {
+    nmethod *saved_code = CodeCache::find_and_remove_saved_code(this);
+    if (saved_code != NULL) {
+      methodHandle method(this);
+      assert( ! saved_code->is_osr_method(), "should not get here for osr" );
+      set_code( method, saved_code );
+    }
+  }
+
   assert(_from_compiled_entry != NULL, "must be set");
   return _from_compiled_entry;
 }
@@ -733,8 +743,8 @@
   int comp_level = code->comp_level();
   // In theory there could be a race here. In practice it is unlikely
   // and not worth worrying about.
-  if (comp_level > highest_tier_compile()) {
-    set_highest_tier_compile(comp_level);
+  if (comp_level > mh->highest_tier_compile()) {
+    mh->set_highest_tier_compile(comp_level);
   }
 
   OrderAccess::storestore();
--- a/hotspot/src/share/vm/oops/methodOop.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/oops/methodOop.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -303,7 +303,7 @@
   bool check_code() const;      // Not inline to avoid circular ref
   nmethod* volatile code() const                 { assert( check_code(), "" ); return (nmethod *)OrderAccess::load_ptr_acquire(&_code); }
   void clear_code();            // Clear out any compiled code
-  void set_code(methodHandle mh, nmethod* code);
+  static void set_code(methodHandle mh, nmethod* code);
   void set_adapter_entry(AdapterHandlerEntry* adapter) {  _adapter = adapter; }
   address get_i2c_entry();
   address get_c2i_entry();
--- a/hotspot/src/share/vm/opto/output.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/opto/output.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -1093,7 +1093,7 @@
   cb->initialize(total_req, locs_req);
 
   // Have we run out of code space?
-  if (cb->blob() == NULL) {
+  if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
     turn_off_compiler(this);
     return;
   }
@@ -1314,7 +1314,7 @@
 
       // Verify that there is sufficient space remaining
       cb->insts()->maybe_expand_to_ensure_remaining(MAX_inst_size);
-      if (cb->blob() == NULL) {
+      if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
         turn_off_compiler(this);
         return;
       }
@@ -1433,7 +1433,7 @@
   }
 
   // One last check for failed CodeBuffer::expand:
-  if (cb->blob() == NULL) {
+  if ((cb->blob() == NULL) || (!CompileBroker::should_compile_new_jobs())) {
     turn_off_compiler(this);
     return;
   }
--- a/hotspot/src/share/vm/runtime/compilationPolicy.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/compilationPolicy.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -66,7 +66,7 @@
   if (!canBeCompiled(m))      return false;
 
   return !UseInterpreter ||                                              // must compile all methods
-         (UseCompiler && AlwaysCompileLoopMethods && m->has_loops()); // eagerly compile loop methods
+         (UseCompiler && AlwaysCompileLoopMethods && m->has_loops() && CompileBroker::should_compile_new_jobs()); // eagerly compile loop methods
 }
 
 // Returns true if m is allowed to be compiled
@@ -137,7 +137,7 @@
   reset_counter_for_invocation_event(m);
   const char* comment = "count";
 
-  if (!delayCompilationDuringStartup() && canBeCompiled(m) && UseCompiler) {
+  if (!delayCompilationDuringStartup() && canBeCompiled(m) && UseCompiler && CompileBroker::should_compile_new_jobs()) {
     nmethod* nm = m->code();
     if (nm == NULL ) {
       const char* comment = "count";
@@ -162,7 +162,7 @@
   int hot_count = m->backedge_count();
   const char* comment = "backedge_count";
 
-  if (!m->is_not_osr_compilable() && !delayCompilationDuringStartup() && canBeCompiled(m)) {
+  if (!m->is_not_osr_compilable() && !delayCompilationDuringStartup() && canBeCompiled(m) && CompileBroker::should_compile_new_jobs()) {
     CompileBroker::compile_method(m, loop_top_bci, m, hot_count, comment, CHECK);
 
     NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(loop_top_bci));)
@@ -204,7 +204,7 @@
   reset_counter_for_invocation_event(m);
   const char* comment = "count";
 
-  if (m->code() == NULL && !delayCompilationDuringStartup() && canBeCompiled(m) && UseCompiler) {
+  if (m->code() == NULL && !delayCompilationDuringStartup() && canBeCompiled(m) && UseCompiler && CompileBroker::should_compile_new_jobs()) {
     ResourceMark rm(THREAD);
     JavaThread *thread = (JavaThread*)THREAD;
     frame       fr     = thread->last_frame();
@@ -248,7 +248,7 @@
   int hot_count = m->backedge_count();
   const char* comment = "backedge_count";
 
-  if (!m->is_not_osr_compilable() && !delayCompilationDuringStartup() && canBeCompiled(m)) {
+  if (!m->is_not_osr_compilable() && !delayCompilationDuringStartup() && canBeCompiled(m) && CompileBroker::should_compile_new_jobs()) {
     CompileBroker::compile_method(m, loop_top_bci, m, hot_count, comment, CHECK);
 
     NOT_PRODUCT(trace_osr_completion(m->lookup_osr_nmethod_for(loop_top_bci));)
--- a/hotspot/src/share/vm/runtime/globals.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/globals.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -3117,6 +3117,15 @@
   notproduct(bool, ExitOnFullCodeCache, false,                              \
           "Exit the VM if we fill the code cache.")                         \
                                                                             \
+  product(bool, UseCodeCacheFlushing, false,                                \
+          "Attempt to clean the code cache before shutting off compiler")   \
+                                                                            \
+  product(intx,  MinCodeCacheFlushingInterval, 30,                          \
+          "Min number of seconds between code cache cleaning sessions")     \
+                                                                            \
+  product(uintx,  CodeCacheFlushingMinimumFreeSpace, 1500*K,                \
+          "When less than X space left, start code cache cleaning")         \
+                                                                            \
   /* interpreter debugging */                                               \
   develop(intx, BinarySwitchThreshold, 5,                                   \
           "Minimal number of lookupswitch entries for rewriting to binary " \
--- a/hotspot/src/share/vm/runtime/sharedRuntime.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/sharedRuntime.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -2146,19 +2146,8 @@
       // CodeCache is full, disable compilation
       // Ought to log this but compile log is only per compile thread
       // and we're some non descript Java thread.
-      UseInterpreter = true;
-      if (UseCompiler || AlwaysCompileLoopMethods ) {
-#ifndef PRODUCT
-        warning("CodeCache is full. Compiler has been disabled");
-        if (CompileTheWorld || ExitOnFullCodeCache) {
-          before_exit(JavaThread::current());
-          exit_globals(); // will delete tty
-          vm_direct_exit(CompileTheWorld ? 0 : 1);
-        }
-#endif
-        UseCompiler               = false;
-        AlwaysCompileLoopMethods  = false;
-      }
+      MutexUnlocker mu(AdapterHandlerLibrary_lock);
+      CompileBroker::handle_full_code_cache();
       return NULL; // Out of CodeCache space
     }
     entry->relocate(B->instructions_begin());
@@ -2282,19 +2271,8 @@
     // CodeCache is full, disable compilation
     // Ought to log this but compile log is only per compile thread
     // and we're some non descript Java thread.
-    UseInterpreter = true;
-    if (UseCompiler || AlwaysCompileLoopMethods ) {
-#ifndef PRODUCT
-      warning("CodeCache is full. Compiler has been disabled");
-      if (CompileTheWorld || ExitOnFullCodeCache) {
-        before_exit(JavaThread::current());
-        exit_globals(); // will delete tty
-        vm_direct_exit(CompileTheWorld ? 0 : 1);
-      }
-#endif
-      UseCompiler               = false;
-      AlwaysCompileLoopMethods  = false;
-    }
+    MutexUnlocker mu(AdapterHandlerLibrary_lock);
+    CompileBroker::handle_full_code_cache();
   }
   return nm;
 }
--- a/hotspot/src/share/vm/runtime/sweeper.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/sweeper.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -33,6 +33,11 @@
 jint      NMethodSweeper::_locked_seen = 0;
 jint      NMethodSweeper::_not_entrant_seen_on_stack = 0;
 bool      NMethodSweeper::_rescan = false;
+bool      NMethodSweeper::_was_full = false;
+jint      NMethodSweeper::_advise_to_sweep = 0;
+jlong     NMethodSweeper::_last_was_full = 0;
+uint      NMethodSweeper::_highest_marked = 0;
+long      NMethodSweeper::_was_full_traversal = 0;
 
 class MarkActivationClosure: public CodeBlobClosure {
 public:
@@ -114,6 +119,40 @@
       tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep");
     }
   }
+
+  if (UseCodeCacheFlushing) {
+    if (!CodeCache::needs_flushing()) {
+      // In a safepoint, no race with setters
+      _advise_to_sweep = 0;
+    }
+
+    if (was_full()) {
+      // There was some progress so attempt to restart the compiler
+      jlong now           = os::javaTimeMillis();
+      jlong max_interval  = (jlong)MinCodeCacheFlushingInterval * (jlong)1000;
+      jlong curr_interval = now - _last_was_full;
+      if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) {
+        CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
+        set_was_full(false);
+
+        // Update the _last_was_full time so we can tell how fast the
+        // code cache is filling up
+        _last_was_full = os::javaTimeMillis();
+
+        if (PrintMethodFlushing) {
+          tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
+            CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+        }
+        if (LogCompilation && (xtty != NULL)) {
+          ttyLocker ttyl;
+          xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
+                           CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+          xtty->stamp();
+          xtty->end_elem();
+        }
+      }
+    }
+  }
 }
 
 
@@ -137,12 +176,12 @@
     if (nm->is_marked_for_reclamation()) {
       assert(!nm->is_locked_by_vm(), "must not flush locked nmethods");
       if (PrintMethodFlushing && Verbose) {
-        tty->print_cr("### Nmethod 0x%x (marked for reclamation) being flushed", nm);
+        tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm);
       }
       nm->flush();
     } else {
       if (PrintMethodFlushing && Verbose) {
-        tty->print_cr("### Nmethod 0x%x (zombie) being marked for reclamation", nm);
+        tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm);
       }
       nm->mark_for_reclamation();
       _rescan = true;
@@ -152,7 +191,7 @@
     // stack we can safely convert it to a zombie method
     if (nm->can_not_entrant_be_converted()) {
       if (PrintMethodFlushing && Verbose) {
-        tty->print_cr("### Nmethod 0x%x (not entrant) being made zombie", nm);
+        tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm);
       }
       nm->make_zombie();
       _rescan = true;
@@ -167,7 +206,7 @@
   } else if (nm->is_unloaded()) {
     // Unloaded code, just make it a zombie
     if (PrintMethodFlushing && Verbose)
-      tty->print_cr("### Nmethod 0x%x (unloaded) being made zombie", nm);
+      tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm);
     if (nm->is_osr_method()) {
       // No inline caches will ever point to osr methods, so we can just remove it
       nm->flush();
@@ -177,7 +216,167 @@
     }
   } else {
     assert(nm->is_alive(), "should be alive");
+
+    if (UseCodeCacheFlushing) {
+      if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) &&
+          (_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) &&
+          CodeCache::needs_flushing()) {
+        // This method has not been called since the forced cleanup happened
+        nm->make_not_entrant();
+      }
+    }
+
     // Clean-up all inline caches that points to zombie/non-reentrant methods
     nm->cleanup_inline_caches();
   }
 }
+
+// Code cache unloading: when compilers notice the code cache is getting full,
+// they will call a vm op that comes here. This code attempts to speculatively
+// unload the oldest half of the nmethods (based on the compile job id) by
+// saving the old code in a list in the CodeCache. Then
+// execution resumes. If a method so marked is not called by the second
+// safepoint from the current one, the nmethod will be marked non-entrant and
+// got rid of by normal sweeping. If the method is called, the methodOop's
+// _code field is restored and the methodOop/nmethod
+// go back to their normal state.
+void NMethodSweeper::handle_full_code_cache(bool is_full) {
+  // Only the first one to notice can advise us to start early cleaning
+  if (!is_full){
+    jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 );
+    if (old != 0) {
+      return;
+    }
+  }
+
+  if (is_full) {
+    // Since code cache is full, immediately stop new compiles
+    bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation);
+    if (!did_set) {
+      // only the first to notice can start the cleaning,
+      // others will go back and block
+      return;
+    }
+    set_was_full(true);
+
+    // If we run out within MinCodeCacheFlushingInterval of the last unload time, give up
+    jlong now = os::javaTimeMillis();
+    jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000;
+    jlong curr_interval = now - _last_was_full;
+    if (curr_interval < max_interval) {
+      _rescan = true;
+      if (PrintMethodFlushing) {
+        tty->print_cr("### handle full too often, turning off compiler");
+      }
+      if (LogCompilation && (xtty != NULL)) {
+        ttyLocker ttyl;
+        xtty->begin_elem("disable_compiler flushing_interval='" UINT64_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
+                         curr_interval/1000, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+        xtty->stamp();
+        xtty->end_elem();
+      }
+      return;
+    }
+  }
+
+  VM_HandleFullCodeCache op(is_full);
+  VMThread::execute(&op);
+
+  // rescan again as soon as possible
+  _rescan = true;
+}
+
+void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) {
+  // If there was a race in detecting full code cache, only run
+  // one vm op for it or keep the compiler shut off
+
+  debug_only(jlong start = os::javaTimeMillis();)
+
+  if ((!was_full()) && (is_full)) {
+    if (!CodeCache::needs_flushing()) {
+      if (PrintMethodFlushing) {
+        tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
+          CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+      }
+      if (LogCompilation && (xtty != NULL)) {
+        ttyLocker ttyl;
+        xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
+                         CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+        xtty->stamp();
+        xtty->end_elem();
+      }
+      CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
+      return;
+    }
+  }
+
+  // Traverse the code cache trying to dump the oldest nmethods
+  uint curr_max_comp_id = CompileBroker::get_compilation_id();
+  uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked;
+  if (PrintMethodFlushing && Verbose) {
+    tty->print_cr("### Cleaning code cache: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes",
+        CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+  }
+  if (LogCompilation && (xtty != NULL)) {
+    ttyLocker ttyl;
+    xtty->begin_elem("start_cleaning_code_cache live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
+                      CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+    xtty->stamp();
+    xtty->end_elem();
+  }
+
+  nmethod* nm = CodeCache::alive_nmethod(CodeCache::first());
+  jint disconnected = 0;
+  jint made_not_entrant  = 0;
+  while ((nm != NULL)){
+    uint curr_comp_id = nm->compile_id();
+
+    // OSR methods cannot be flushed like this. Also, don't flush native methods
+    // since they are part of the JDK in most cases
+    if (nm->is_in_use() && (!nm->is_osr_method()) && (!nm->is_locked_by_vm()) &&
+        (!nm->is_native_method()) && ((curr_comp_id < flush_target))) {
+
+      if ((nm->method()->code() == nm)) {
+        // This method has not been previously considered for
+        // unloading or it was restored already
+        CodeCache::speculatively_disconnect(nm);
+        disconnected++;
+      } else if (nm->is_speculatively_disconnected()) {
+        // This method was previously considered for preemptive unloading and was not called since then
+        nm->method()->invocation_counter()->decay();
+        nm->method()->backedge_counter()->decay();
+        nm->make_not_entrant();
+        made_not_entrant++;
+      }
+
+      if (curr_comp_id > _highest_marked) {
+        _highest_marked = curr_comp_id;
+      }
+    }
+    nm = CodeCache::alive_nmethod(CodeCache::next(nm));
+  }
+
+  if (LogCompilation && (xtty != NULL)) {
+    ttyLocker ttyl;
+    xtty->begin_elem("stop_cleaning_code_cache disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
+                      disconnected, made_not_entrant, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
+    xtty->stamp();
+    xtty->end_elem();
+  }
+
+  // Shut off compiler. Sweeper will run exiting from this safepoint
+  // and turn it back on if it clears enough space
+  if (was_full()) {
+    _last_was_full = os::javaTimeMillis();
+    CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation);
+  }
+
+  // After two more traversals the sweeper will get rid of unrestored nmethods
+  _was_full_traversal = _traversals;
+#ifdef ASSERT
+  jlong end = os::javaTimeMillis();
+  if(PrintMethodFlushing && Verbose) {
+    tty->print_cr("### sweeper: unload time: " INT64_FORMAT, end-start);
+  }
+#endif
+}
--- a/hotspot/src/share/vm/runtime/sweeper.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/sweeper.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -38,6 +38,11 @@
   static int       _locked_seen;     // Number of locked nmethods encountered during the scan
   static int       _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack
 
+  static bool      _was_full;        // remember if we did emergency unloading
+  static jint      _advise_to_sweep; // flag to indicate code cache getting full
+  static jlong     _last_was_full;   // timestamp of last emergency unloading
+  static uint      _highest_marked;   // highest compile id dumped at last emergency unloading
+  static long      _was_full_traversal;   // trav number at last emergency unloading
 
   static void process_nmethod(nmethod *nm);
  public:
@@ -51,4 +56,10 @@
     // changes to false at safepoint so we can never overwrite it with false.
      _rescan = true;
   }
+
+  static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate
+  static void speculative_disconnect_nmethods(bool was_full);   // Called by vm op to deal with alloc failure
+
+  static void set_was_full(bool state) { _was_full = state; }
+  static bool was_full() { return _was_full; }
 };
--- a/hotspot/src/share/vm/runtime/vm_operations.cpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/vm_operations.cpp	Fri Jan 29 09:27:22 2010 -0800
@@ -151,6 +151,10 @@
 
 #endif // !PRODUCT
 
+void VM_HandleFullCodeCache::doit() {
+  NMethodSweeper::speculative_disconnect_nmethods(_is_full);
+}
+
 void VM_Verify::doit() {
   Universe::verify();
 }
--- a/hotspot/src/share/vm/runtime/vm_operations.hpp	Fri Jan 29 08:33:24 2010 -0800
+++ b/hotspot/src/share/vm/runtime/vm_operations.hpp	Fri Jan 29 09:27:22 2010 -0800
@@ -41,6 +41,7 @@
   template(DeoptimizeFrame)                       \
   template(DeoptimizeAll)                         \
   template(ZombieAll)                             \
+  template(HandleFullCodeCache)                   \
   template(Verify)                                \
   template(PrintJNI)                              \
   template(HeapDumper)                            \
@@ -241,6 +242,16 @@
   bool allow_nested_vm_operations() const        { return true;  }
 };
 
+class VM_HandleFullCodeCache: public VM_Operation {
+ private:
+  bool  _is_full;
+ public:
+  VM_HandleFullCodeCache(bool is_full)           { _is_full = is_full; }
+  VMOp_Type type() const                         { return VMOp_HandleFullCodeCache; }
+  void doit();
+  bool allow_nested_vm_operations() const        { return true; }
+};
+
 #ifndef PRODUCT
 class VM_DeoptimizeAll: public VM_Operation {
  private: