Allow Last Responder thread pointer to be NULL

Last Responder thread can be NULL in the case of Safe Point Exclusive. Check pointer for NULL and leave thread name empty. Signed-off-by: Dmitri Pivkine <[email protected]>
dmitripivkine · Oct 24, 2023 · 22e3979 · 22e3979
1 parent 501add5
commit 22e3979
Showing 1 changed file with 12 additions and 4 deletions.
diff --git a/gc/verbose/VerboseHandlerOutput.cpp b/gc/verbose/VerboseHandlerOutput.cpp
@@ -598,8 +598,12 @@ MM_VerboseHandlerOutput::handleExclusiveStart(J9HookInterface** hook, uintptr_t
 	manager->setLastExclusiveAccessStartTime(currentTime);
 
 	OMR_VMThread* lastResponder = event->lastResponder;
-	char escapedLastResponderName[64];
-	getThreadName(escapedLastResponderName,sizeof(escapedLastResponderName),lastResponder);
+	char escapedLastResponderName[64] = "";
+
+	/* Last Responder thread can be passed NULL in the case of Safe Point Exclusive */
+	if (NULL != lastResponder) {
+		getThreadName(escapedLastResponderName, sizeof(escapedLastResponderName), lastResponder);
+	}
 
 	char tagTemplate[200];
 	getTagTemplate(tagTemplate, sizeof(tagTemplate), manager->getIdAndIncrement(), omrtime_current_time_millis());
@@ -608,8 +612,12 @@ MM_VerboseHandlerOutput::handleExclusiveStart(J9HookInterface** hook, uintptr_t
 		writer->formatAndOutput(env, 0, "<warning details=\"clock error detected, following timing may be inaccurate\" />");
 	}	
 	writer->formatAndOutput(env, 0, "<exclusive-start %s intervalms=\"%llu.%03.3llu\">", tagTemplate, deltaTime / 1000, deltaTime % 1000);
-	writer->formatAndOutput(env, 1, "<response-info timems=\"%llu.%03.3llu\" idlems=\"%llu.%03.3llu\" threads=\"%zu\" lastid=\"%p\" lastname=\"%s\" />",
-			exclusiveAccessTime / 1000, exclusiveAccessTime % 1000, meanIdleTime / 1000, meanIdleTime % 1000, event->haltedThreads, (NULL == lastResponder ? NULL : lastResponder->_language_vmthread), escapedLastResponderName);
+
+	writer->formatAndOutput(
+		env, 1, "<response-info timems=\"%llu.%03.3llu\" idlems=\"%llu.%03.3llu\" threads=\"%zu\" lastid=\"%p\" lastname=\"%s\" />",
+		exclusiveAccessTime / 1000, exclusiveAccessTime % 1000, meanIdleTime / 1000, meanIdleTime % 1000, event->haltedThreads,
+		(NULL == lastResponder ? NULL : lastResponder->_language_vmthread), escapedLastResponderName);
+
 	writer->formatAndOutput(env, 0, "</exclusive-start>");
 	writer->flush(env);
 	exitAtomicReportingBlock();