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Add information regarding synchronous compilations in javacore #24236

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Add information regarding synchronous compilations in javacore
dev-koan Jun 24, 2026
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dev-koan Jul 23, 2026
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dev-koan Jul 24, 2026
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dev-koan Jul 24, 2026
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3 changes: 3 additions & 0 deletions runtime/compiler/control/CompilationRuntime.hpp
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Expand Up @@ -512,6 +512,8 @@ class CompilationInfo {
}
}; // CompilationStatsPerInterval

typedef J9JITSyncCompilationStatistics SyncCompilationStatistics;

@keithc-ca keithc-ca Jul 29, 2026

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This doesn't appear to be used anywhere: Please remove it.


static bool createCompilationInfo(J9JITConfig *jitConfig);
static void freeCompilationInfo(J9JITConfig *jitConfig);

Expand Down Expand Up @@ -1508,6 +1510,7 @@ class CompilationInfo {

struct CompilationStatistics _stats;
struct CompilationStatsPerInterval _intervalStats;
SyncCompilationStatistics _syncCompStats;
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TR_PersistentArray<TR_SignatureCountPair *> *_persistedMethods;

// Must be less than 16 at the JITClient or non-JITServer mode because
Expand Down
80 changes: 80 additions & 0 deletions runtime/compiler/control/CompilationThread.cpp
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Expand Up @@ -21,6 +21,7 @@
* Assisted-by: IBM Bob
*******************************************************************************/

#include <cstdint>
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#define J9_EXTERNAL_TO_VM

#if SOLARIS || AIXPPC || LINUX || OSX
Expand Down Expand Up @@ -807,6 +808,7 @@ bool TR::CompilationInfo::createCompilationInfo(J9JITConfig *jitConfig)
memset(alloc, 0, sizeof(TR::CompilationInfo));
_compilationRuntime = new (alloc) TR::CompilationInfo(jitConfig);
jitConfig->compilationRuntime = (void *)_compilationRuntime;
jitConfig->syncCompStats = &_compilationRuntime->_syncCompStats;
#ifdef DEBUG
if (debug("traceThreadCompile"))
_compilationRuntime->_traceCompiling = true;
Expand Down Expand Up @@ -857,6 +859,19 @@ void TR::CompilationInfo::freeAllResources()
}

freeAllCompilationThreads();

PORT_ACCESS_FROM_JITCONFIG(_jitConfig);
for (int32_t i = 0; i < J9_NUM_LONGEST_SYNC_COMP; i++) {
J9JITLongestSyncComp &longestWaitMethod = _syncCompStats.longestWaitMethods[i];
if (longestWaitMethod.methodName != NULL) {
j9mem_free_memory(longestWaitMethod.methodName);
longestWaitMethod.methodName = NULL;
}
if (longestWaitMethod.threadName != NULL) {
j9mem_free_memory(longestWaitMethod.threadName);
longestWaitMethod.threadName = NULL;
}
}
}

void TR::CompilationInfo::freeCompilationInfo(J9JITConfig *jitConfig)
Expand Down Expand Up @@ -6182,6 +6197,12 @@ void *TR::CompilationInfo::compileOnSeparateThread(J9VMThread *vmThread, TR::IlG
//
entry->_numThreadsWaiting++;

uint64_t waitStart = 0;
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PORT_ACCESS_FROM_JITCONFIG(_jitConfig);

@keithc-ca keithc-ca Jul 29, 2026

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With this, line 6375 provides a duplicate local; that line should be removed.

if (!async) {
waitStart = j9time_hires_clock();
}

// Release the compilation monitor
//
debugPrint(vmThread, "\tapplication thread releasing compilation monitor\n");
Expand Down Expand Up @@ -6279,6 +6300,65 @@ void *TR::CompilationInfo::compileOnSeparateThread(J9VMThread *vmThread, TR::IlG

entry->_numThreadsWaiting--;

if (!async) {
uint64_t waitEnd = j9time_hires_clock();
uint64_t duration = j9time_hires_delta(waitStart, waitEnd, J9PORT_TIME_DELTA_IN_MICROSECONDS);

_syncCompStats.totalCount++;
_syncCompStats.totalWaitTime += duration;

/* Obtain index to insert. */
int idx = -1;

@keithc-ca keithc-ca Jul 24, 2026

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This should use the same type as i.

@dev-koan dev-koan Jul 24, 2026

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Updated.

for (int32_t i = 0; i < J9_NUM_LONGEST_SYNC_COMP; i++) {
if (_syncCompStats.longestWaitMethods[i].waitTime < duration) {
idx = i;
break;
}
}

if (0 <= idx) {
/* Remove the shortest wait-time. */
J9JITLongestSyncComp &lastMethod = _syncCompStats.longestWaitMethods[J9_NUM_LONGEST_SYNC_COMP - 1];
if (NULL != lastMethod.methodName) {
j9mem_free_memory(lastMethod.methodName);
lastMethod.methodName = NULL;
}
if (NULL != lastMethod.threadName) {
j9mem_free_memory(lastMethod.threadName);
lastMethod.threadName = NULL;
}
for (int32_t i = J9_NUM_LONGEST_SYNC_COMP - 1; i > idx; i--) {
_syncCompStats.longestWaitMethods[i] = _syncCompStats.longestWaitMethods[i - 1];
}

_syncCompStats.longestWaitMethods[idx].waitTime = duration;
_syncCompStats.longestWaitMethods[idx].waitTimeEnd = j9time_current_time_millis();

J9UTF8 *className = NULL;
J9UTF8 *name = NULL;
J9UTF8 *signature = NULL;
getClassNameSignatureFromMethod(method, className, name, signature);

uint32_t totalLen = J9UTF8_LENGTH(className) + J9UTF8_LENGTH(name) + J9UTF8_LENGTH(signature) + 2;
char *templongestWaitMethod = (char *)j9mem_allocate_memory(totalLen, J9MEM_CATEGORY_JIT);
if (NULL != templongestWaitMethod) {
j9str_printf(templongestWaitMethod, totalLen, "%.*s.%.*s%.*s", J9UTF8_LENGTH(className),
J9UTF8_DATA(className), J9UTF8_LENGTH(name), J9UTF8_DATA(name), J9UTF8_LENGTH(signature),
J9UTF8_DATA(signature));
}
_syncCompStats.longestWaitMethods[idx].methodName = templongestWaitMethod;

const char *threadName = getOMRVMThreadName(vmThread->omrVMThread);
uint32_t len = strlen(threadName);
char *tempThread = (char *)j9mem_allocate_memory(len + 1, J9MEM_CATEGORY_JIT);
if (NULL != tempThread) {
memcpy(tempThread, threadName, len + 1);
}
_syncCompStats.longestWaitMethods[idx].threadName = tempThread;
releaseOMRVMThreadName(vmThread->omrVMThread);
}
}

TR_ASSERT_FATAL(!(entry->_freeTag & (ENTRY_DEALLOCATED | ENTRY_IN_POOL_FREE)),
"Java thread waking up with a freed entry");

Expand Down
17 changes: 17 additions & 0 deletions runtime/oti/j9nonbuilder.h
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Expand Up @@ -297,6 +297,9 @@
#define J9_CATCHTYPE_VALUE_FOR_SYNTHETIC_HANDLER_4BYTES 0xFFFFFFFF
#define J9_CATCHTYPE_VALUE_FOR_SYNTHETIC_HANDLER_2BYTES 0xFFFF

/* Constant for information regarding longest synchronous compilations. */
#define J9_NUM_LONGEST_SYNC_COMP 3

#if JAVA_SPEC_VERSION >= 19
#define J9JVMTI_MAX_TLS_KEYS 124
typedef void(*j9_tls_finalizer_t)(void *);
Expand Down Expand Up @@ -4376,6 +4379,19 @@ typedef struct J9ClassCastParms {
struct J9Class* castClass;
} J9ClassCastParms;

typedef struct J9JITLongestSyncComp {
uint64_t waitTime; /* microseconds */
uint64_t waitTimeEnd; /* absolute timestamp */
char *methodName;
char *threadName;
} J9JITLongestSyncComp;

typedef struct J9JITSyncCompilationStatistics {
uint32_t totalCount;
uint64_t totalWaitTime; /* microseconds */
J9JITLongestSyncComp longestWaitMethods[J9_NUM_LONGEST_SYNC_COMP]; /* sorted in increasing order */

@keithc-ca keithc-ca Jul 24, 2026

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I think you mean "decreasing" (the first entry has the longest wait time).

@dev-koan dev-koan Jul 24, 2026

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Updated.

} J9JITSyncCompilationStatistics;

/* @ddr_namespace: map_to_type=J9JITConfig */

typedef struct J9JITConfig {
Expand Down Expand Up @@ -4649,6 +4665,7 @@ typedef struct J9JITConfig {
IDATA verboseOutputLevel;
omrthread_monitor_t compilationMonitor;
void* compilationInfo;
J9JITSyncCompilationStatistics *syncCompStats;
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void* aotCompilationInfo;
void* pseudoTOC;
void* i2jTransition;
Expand Down
76 changes: 76 additions & 0 deletions runtime/rasdump/javadump.cpp
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Expand Up @@ -21,6 +21,7 @@
*******************************************************************************/

/* Includes */
#include <cstdint>

@keithc-ca keithc-ca Jul 24, 2026

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I don't think this is necessary.

@dev-koan dev-koan Jul 24, 2026

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Updated.

#if defined(AIXPPC)
#include <sys/time.h>
#endif /* defined(AIXPPC) */
Expand Down Expand Up @@ -307,6 +308,7 @@ private :
void writeMonitorSection(void);
void writeThreadSection(void);
void writeClassSection(void);
void writeSynchronousCompilationSection(void);
#if defined(OMR_OPT_CUDA)
void writeCudaSection(void);
#endif /* defined(OMR_OPT_CUDA) */
Expand Down Expand Up @@ -556,6 +558,7 @@ JavaCoreDumpWriter::JavaCoreDumpWriter(
CALL_PROTECT(writeSharedClassSection, _Error);
#endif
CALL_PROTECT(writeClassSection, _Error);
CALL_PROTECT(writeSynchronousCompilationSection, _Error);
CALL_PROTECT(writeTrailer, _Error);

/* Record the status of the operation */
Expand Down Expand Up @@ -2915,6 +2918,79 @@ JavaCoreDumpWriter::writeHookSection(void)
_OutputStream.writeCharacters("NULL ------------------------------------------------------------------------\n");
}

void
JavaCoreDumpWriter::writeSynchronousCompilationSection(void)
{
char timeStamp[_MaximumTimeStampLength + 1];
PORT_ACCESS_FROM_PORT(_PortLibrary);
OMRPORT_ACCESS_FROM_J9PORT(PORTLIB);

J9JITConfig *jitConfig = _VirtualMachine->jitConfig;
if ((NULL == jitConfig) || (NULL == jitConfig->syncCompStats)) {
return;
}

J9JITSyncCompilationStatistics *stats = jitConfig->syncCompStats;

_OutputStream.writeCharacters("0SECTION Synchronous compilations info dump routine\n");
_OutputStream.writeCharacters("NULL ==============================\n");
_OutputStream.writeCharacters("1NOTE This data is reset after each javacore file is written\n");
_OutputStream.writeCharacters("NULL ------------------------------------------------------------------------\n");
_OutputStream.writeCharacters("1JITSYNCSTATS Synchronous Compilation Statistics\n");
_OutputStream.writeCharacters("NULL ------------------------------------------------------------------------\n");
_OutputStream.writeCharacters("2JITSYNCCOUNT Total synchronous compilations: ");
_OutputStream.writeInteger(stats->totalCount, "%u");
_OutputStream.writeCharacters("\n");
_OutputStream.writeCharacters("2JITTOTALWAIT Total application wait time: ");
_OutputStream.writeInteger64(stats->totalWaitTime, "%llu");
_OutputStream.writeCharacters("us\n");
for (int32_t i = 0; i < J9_NUM_LONGEST_SYNC_COMP; i++) {

@keithc-ca keithc-ca Jul 24, 2026

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Suggest using UDATA instead of int32_t, in part so the format on line 2953 is correct, and for consistency with other loops in this file.

@dev-koan dev-koan Jul 24, 2026

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Updated.

J9JITLongestSyncComp &longestWaitMethod = stats->longestWaitMethods[i];
if ((0 == longestWaitMethod.waitTime) || (NULL == longestWaitMethod.methodName)) {
break;
}
_OutputStream.writeCharacters("2JITLONGEST ");
_OutputStream.writeInteger(i + 1, "%zu");
_OutputStream.writeCharacters(". Longest Synchronous Compilation\n");

_OutputStream.writeCharacters("3JITWAITTIME Wait time: ");
_OutputStream.writeInteger(longestWaitMethod.waitTime, "%llu");
_OutputStream.writeCharacters("us\n");

_OutputStream.writeCharacters("3JITENDTIME Wait time end: ");
omrstr_ftime_ex(timeStamp, _MaximumTimeStampLength, "%Y-%m-%dT%H:%M:%S",
longestWaitMethod.waitTimeEnd, OMRSTR_FTIME_FLAG_LOCAL);

@keithc-ca keithc-ca Jul 24, 2026

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Excessive indentation: Two tabs more than line 2961 is sufficient.

@dev-koan dev-koan Jul 24, 2026

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Updated.

timeStamp[_MaximumTimeStampLength] = '\0';
_OutputStream.writeCharacters(timeStamp);
_OutputStream.writeInteger64(longestWaitMethod.waitTimeEnd % 1000, ".%03llu");
_OutputStream.writeCharacters("\n");

_OutputStream.writeCharacters("3JITMETHOD Method: ");
_OutputStream.writeCharacters(longestWaitMethod.methodName);
_OutputStream.writeCharacters("\n");

_OutputStream.writeCharacters("3JITTHREAD Thread: ");
_OutputStream.writeCharacters(longestWaitMethod.threadName);
_OutputStream.writeCharacters("\n");
}

stats->totalCount = 0;
stats->totalWaitTime = 0;
for (int32_t i = 0; i < J9_NUM_LONGEST_SYNC_COMP; i++) {
J9JITLongestSyncComp &longestWaitMethod = stats->longestWaitMethods[i];
longestWaitMethod.waitTime = 0;
longestWaitMethod.waitTimeEnd = 0;
if (NULL != longestWaitMethod.methodName) {
j9mem_free_memory(longestWaitMethod.methodName);
longestWaitMethod.methodName = NULL;
}
if (NULL != longestWaitMethod.threadName) {
j9mem_free_memory(longestWaitMethod.threadName);
longestWaitMethod.threadName = NULL;
}
}
}

#if defined(OMR_OPT_CUDA)

/**
Expand Down