8075214: SIGSEGV in nmethod sweeping
Changed implementation of forceNMethodSweep() to request sweep from existing sweeper thread.
Reviewed-by: kvn, mgerdin, dholmes
diff --git a/hotspot/src/share/vm/prims/whitebox.cpp b/hotspot/src/share/vm/prims/whitebox.cpp
index 3c833ce..f9f9390 100644
--- a/hotspot/src/share/vm/prims/whitebox.cpp
+++ b/hotspot/src/share/vm/prims/whitebox.cpp
@@ -819,46 +819,9 @@
mo.notify_all();
WB_END
-void WhiteBox::sweeper_thread_entry(JavaThread* thread, TRAPS) {
- guarantee(WhiteBoxAPI, "internal testing API :: WhiteBox has to be enabled");
- {
- MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
- NMethodSweeper::_should_sweep = true;
- }
- NMethodSweeper::possibly_sweep();
-}
-
-JavaThread* WhiteBox::create_sweeper_thread(TRAPS) {
- // create sweeper thread w/ custom entry -- one iteration instead of loop
- CodeCacheSweeperThread* sweeper_thread = new CodeCacheSweeperThread();
- sweeper_thread->set_entry_point(&WhiteBox::sweeper_thread_entry);
-
- // create j.l.Thread object and associate it w/ sweeper thread
- {
- // inherit deamon property from current thread
- bool is_daemon = java_lang_Thread::is_daemon(JavaThread::current()->threadObj());
-
- HandleMark hm(THREAD);
- Handle thread_group(THREAD, Universe::system_thread_group());
- const char* name = "WB Sweeper thread";
- sweeper_thread->allocate_threadObj(thread_group, name, is_daemon, THREAD);
- }
-
- {
- MutexLocker mu(Threads_lock, THREAD);
- Threads::add(sweeper_thread);
- }
- return sweeper_thread;
-}
-
-WB_ENTRY(jobject, WB_ForceNMethodSweep(JNIEnv* env, jobject o))
- JavaThread* sweeper_thread = WhiteBox::create_sweeper_thread(Thread::current());
- if (sweeper_thread == NULL) {
- return NULL;
- }
- jobject result = JNIHandles::make_local(env, sweeper_thread->threadObj());
- Thread::start(sweeper_thread);
- return result;
+WB_ENTRY(void, WB_ForceNMethodSweep(JNIEnv* env, jobject o))
+ // Force a code cache sweep and block until it finished
+ NMethodSweeper::force_sweep();
WB_END
WB_ENTRY(jboolean, WB_IsInStringTable(JNIEnv* env, jobject o, jstring javaString))
@@ -1402,7 +1365,7 @@
{CC"getCPUFeatures", CC"()Ljava/lang/String;", (void*)&WB_GetCPUFeatures },
{CC"getNMethod", CC"(Ljava/lang/reflect/Executable;Z)[Ljava/lang/Object;",
(void*)&WB_GetNMethod },
- {CC"forceNMethodSweep0", CC"()Ljava/lang/Thread;", (void*)&WB_ForceNMethodSweep },
+ {CC"forceNMethodSweep", CC"()V", (void*)&WB_ForceNMethodSweep },
{CC"allocateCodeBlob", CC"(II)J", (void*)&WB_AllocateCodeBlob },
{CC"freeCodeBlob", CC"(J)V", (void*)&WB_FreeCodeBlob },
{CC"getCodeHeapEntries", CC"(I)[Ljava/lang/Object;",(void*)&WB_GetCodeHeapEntries },
diff --git a/hotspot/src/share/vm/prims/whitebox.hpp b/hotspot/src/share/vm/prims/whitebox.hpp
index 5975427..3ebada8 100644
--- a/hotspot/src/share/vm/prims/whitebox.hpp
+++ b/hotspot/src/share/vm/prims/whitebox.hpp
@@ -70,8 +70,6 @@
Symbol* signature_symbol);
static const char* lookup_jstring(const char* field_name, oop object);
static bool lookup_bool(const char* field_name, oop object);
- static void sweeper_thread_entry(JavaThread* thread, TRAPS);
- static JavaThread* create_sweeper_thread(TRAPS);
static int get_blob_type(const CodeBlob* code);
static CodeHeap* get_code_heap(int blob_type);
static CodeBlob* allocate_code_blob(int size, int blob_type);
diff --git a/hotspot/src/share/vm/runtime/sweeper.cpp b/hotspot/src/share/vm/runtime/sweeper.cpp
index c059be0..42d9267 100644
--- a/hotspot/src/share/vm/runtime/sweeper.cpp
+++ b/hotspot/src/share/vm/runtime/sweeper.cpp
@@ -144,6 +144,7 @@
int NMethodSweeper::_seen = 0; // Nof. nmethod we have currently processed in current pass of CodeCache
volatile bool NMethodSweeper::_should_sweep = true; // Indicates if we should invoke the sweeper
+volatile bool NMethodSweeper::_force_sweep = false;// Indicates if we should force a sweep
volatile int NMethodSweeper::_bytes_changed = 0; // Counts the total nmethod size if the nmethod changed from:
// 1) alive -> not_entrant
// 2) not_entrant -> zombie
@@ -276,6 +277,23 @@
}
/**
+ * Wakes up the sweeper thread and forces a sweep. Blocks until it finished.
+ */
+void NMethodSweeper::force_sweep() {
+ ThreadBlockInVM tbivm(JavaThread::current());
+ MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+ // Request forced sweep
+ _force_sweep = true;
+ while (_force_sweep) {
+ // Notify sweeper that we want to force a sweep and wait for completion.
+ // In case a sweep currently takes place we timeout and try again because
+ // we want to enforce a full sweep.
+ CodeCache_lock->notify();
+ CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, 1000);
+ }
+}
+
+/**
* Handle a safepoint request
*/
void NMethodSweeper::handle_safepoint_request() {
@@ -335,6 +353,9 @@
}
}
+ // Remember if this was a forced sweep
+ bool forced = _force_sweep;
+
// Force stack scanning if there is only 10% free space in the code cache.
// We force stack scanning only non-profiled code heap gets full, since critical
// allocation go to the non-profiled heap and we must be make sure that there is
@@ -344,7 +365,7 @@
do_stack_scanning();
}
- if (_should_sweep) {
+ if (_should_sweep || forced) {
init_sweeper_log();
sweep_code_cache();
}
@@ -356,12 +377,20 @@
_should_sweep = false;
// If there was enough state change, 'possibly_enable_sweeper()'
// sets '_should_sweep' to true
- possibly_enable_sweeper();
+ possibly_enable_sweeper();
// Reset _bytes_changed only if there was enough state change. _bytes_changed
// can further increase by calls to 'report_state_change'.
if (_should_sweep) {
_bytes_changed = 0;
}
+
+ if (forced) {
+ // Notify requester that forced sweep finished
+ assert(_force_sweep, "Should be a forced sweep");
+ MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+ _force_sweep = false;
+ CodeCache_lock->notify();
+ }
}
void NMethodSweeper::sweep_code_cache() {
diff --git a/hotspot/src/share/vm/runtime/sweeper.hpp b/hotspot/src/share/vm/runtime/sweeper.hpp
index f0ce1e9..aa4860b 100644
--- a/hotspot/src/share/vm/runtime/sweeper.hpp
+++ b/hotspot/src/share/vm/runtime/sweeper.hpp
@@ -54,7 +54,6 @@
// nmethod's space is freed.
class NMethodSweeper : public AllStatic {
- friend class WhiteBox;
private:
enum MethodStateChange {
None,
@@ -71,6 +70,7 @@
static volatile int _sweep_started; // Flag to control conc sweeper
static volatile bool _should_sweep; // Indicates if we should invoke the sweeper
+ static volatile bool _force_sweep; // Indicates if we should force a sweep
static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from:
// 1) alive -> not_entrant
// 2) not_entrant -> zombie
@@ -117,6 +117,7 @@
static void mark_active_nmethods(); // Invoked at the end of each safepoint
static void sweeper_loop();
static void notify(int code_blob_type); // Possibly start the sweeper thread.
+ static void force_sweep();
static int hotness_counter_reset_val();
static void report_state_change(nmethod* nm);
