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Merged
rkennke merged 4 commits into from
Jul 24, 2026
Merged

fix(codecache): report the real runtime-stubs cache size #681

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85246bd
fix(codecache): report the real runtime-stubs cache size
rkennke Jul 22, 2026
6679e6f
docs(codecache): word runtime-stubs usage as approximate, not "live f…
rkennke Jul 22, 2026
83b5576
docs(codecache): drop stale "approximate/#677" note now that memoryUs…
rkennke Jul 23, 2026
df34493
refactor(codecache): route runtime-stubs usage through JVMSupport
rkennke Jul 23, 2026
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4 changes: 4 additions & 0 deletions ddprof-lib/src/main/cpp/hotspot/hotspotSupport.h
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Expand Up@@ -46,6 +46,10 @@ class HotspotSupport {
returnJitCodeCache::isJitCode(p);
}

staticinlinelonglongruntimeStubsMemoryUsage() {
returnJitCodeCache::runtimeStubsMemoryUsage();
}

// If should load all jmethodIDs
staticinlineboolshouldPreloadJmethodIDs(Arguments& args) {
CStack cstack = args._cstack;
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7 changes: 7 additions & 0 deletions ddprof-lib/src/main/cpp/hotspot/jitCodeCache.cpp
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Expand Up@@ -52,3 +52,10 @@ CodeBlob* JitCodeCache::findRuntimeStub(const void *address) {
_stubs_lock.unlockShared();
return stub;
}

longlongJitCodeCache::runtimeStubsMemoryUsage() {
_stubs_lock.lockShared();
longlong usage = _runtime_stubs.memoryUsage();
_stubs_lock.unlockShared();
return usage;
}
5 changes: 5 additions & 0 deletions ddprof-lib/src/main/cpp/hotspot/jitCodeCache.h
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Expand Up@@ -38,6 +38,11 @@ class JitCodeCache {
}

static CodeBlob* findRuntimeStub(constvoid *address);

// Heap usage of the runtime-stubs code cache, via CodeCache::memoryUsage().
// Read under the shared stubs lock because DynamicCodeGenerated() mutates
// _runtime_stubs (add()/expand()) concurrently.
staticlonglongruntimeStubsMemoryUsage();
staticboolisJitCode(constvoid* pc) {
returnCodeHeap::contains(pc);
}
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3 changes: 3 additions & 0 deletions ddprof-lib/src/main/cpp/jvmSupport.h
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Expand Up@@ -55,6 +55,9 @@ class JVMSupport {
static int walkJavaStack(StackWalkRequest& request);
static inline bool canUnwind(const StackFrame& frame, const void*& pc);
static inline bool isJitCode(const void* pc);
// Live heap usage of the JIT runtime-stubs code cache. HotSpot-only; 0 on
// other VMs (J9/Zing), which have no such cache.
static inline long long runtimeStubsMemoryUsage();

static void loadAllMethodIDsIfNeeded(jvmtiEnv *jvmti, JNIEnv *jni);
static bool loadMethodIDsIfNeeded(jvmtiEnv *jvmti, JNIEnv *jni, jclass klass);
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8 changes: 8 additions & 0 deletions ddprof-lib/src/main/cpp/jvmSupport.inline.h
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Expand Up@@ -26,6 +26,14 @@ bool JVMSupport::isJitCode(const void* pc) {
}
}

long longJVMSupport::runtimeStubsMemoryUsage() {
if (VM::isHotspot()) {
returnHotspotSupport::runtimeStubsMemoryUsage();
} else {
return0;
}
}

// Resolve method pointer to jmethodID
jmethodIDJVMSupport::resolve(constvoid*method) {
if (VM::isHotspot()) {
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7 changes: 6 additions & 1 deletion ddprof-lib/src/main/cpp/profiler.cpp
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Expand Up@@ -24,6 +24,7 @@
#include "j9/j9Support.h"
#include "j9/j9WallClock.h"
#include "jvmSupport.h"
#include "jvmSupport.inline.h"
#include "jvmThread.h"
#include "libraryPatcher.h"
#include "objectSampler.h"
Expand DownExpand Up@@ -1780,8 +1781,12 @@ Error Profiler::dump(const char *path, const int length) {
const CodeCacheArray& native_libs = _libs->native_libs();
Counters::set(CODECACHE_NATIVE_COUNT, native_libs.count());
Counters::set(CODECACHE_NATIVE_SIZE_BYTES, native_libs.memoryUsage());
// The runtime-stubs counter reflects the JIT runtime-stubs code cache, a
// separate cache from the native libraries. Routed through JVMSupport so
// the HotSpot-only implementation stays behind the VM abstraction (0 on
// J9/Zing). Read under its shared lock.
Counters::set(CODECACHE_RUNTIME_STUBS_SIZE_BYTES,
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native_libs.memoryUsage());
JVMSupport::runtimeStubsMemoryUsage());

Error err = Error::OK;
// rotateDictsAndRun rotates the dictionaries, takes lockAll() around the
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