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8359437: Make users and test suite not able to set LockingMode flag #25847

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8359437: Make users and test suite not able to set LockingMode flag #25847

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d0d547e
First try.
fbredber Jun 5, 2025
775c30a
Update after pre-review
fbredber Jun 13, 2025
bf2a8bf
Merge branch 'master' into _remove_locking_mode_fix_tests
fbredber Jun 13, 2025
962a709
Merge remote-tracking branch 'origin/master' into 8359437_locking_mod…
toxaart Jun 13, 2025
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16 changes: 16 additions & 0 deletions src/hotspot/share/prims/whitebox.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/jniHandles.inline.hpp"
#include "runtime/lightweightSynchronizer.hpp"
#include "runtime/lockStack.hpp"
#include "runtime/os.hpp"
#include "runtime/stackFrameStream.inline.hpp"
Expand Down Expand Up @@ -1902,6 +1903,20 @@ WB_ENTRY(jboolean, WB_IsMonitorInflated(JNIEnv* env, jobject wb, jobject obj))
return (jboolean) obj_oop->mark().has_monitor();
WB_END

WB_ENTRY(void, WB_ForceInflateMonitorLockedObject(JNIEnv* env, jobject wb, jobject obj))
oop obj_oop = JNIHandles::resolve(obj);
if (obj_oop->mark().has_monitor()) {
return; // Already inflated
}
ObjectSynchronizer::InflateCause cause = ObjectSynchronizer::InflateCause::inflate_cause_vm_internal;
JavaThread* current = JavaThread::current();
if (LockingMode == LM_LIGHTWEIGHT) {
LightweightSynchronizer::inflate_fast_locked_object(obj_oop, cause, current, current);
} else {
ObjectSynchronizer::inflate(current, obj_oop, cause);
}
WB_END

WB_ENTRY(jboolean, WB_IsAsanEnabled(JNIEnv* env))
return (jboolean) WhiteBox::is_asan_enabled();
WB_END
Expand Down Expand Up @@ -2906,6 +2921,7 @@ static JNINativeMethod methods[] = {
(void*)&WB_AddModuleExportsToAll },
{CC"deflateIdleMonitors", CC"()Z", (void*)&WB_DeflateIdleMonitors },
{CC"isMonitorInflated0", CC"(Ljava/lang/Object;)Z", (void*)&WB_IsMonitorInflated },
{CC"forceInflateMonitorLockedObject0", CC"(Ljava/lang/Object;)V", (void*)&WB_ForceInflateMonitorLockedObject },
{CC"isAsanEnabled", CC"()Z", (void*)&WB_IsAsanEnabled },
{CC"isUbsanEnabled", CC"()Z", (void*)&WB_IsUbsanEnabled },
{CC"getInUseMonitorCount", CC"()J", (void*)&WB_getInUseMonitorCount },
Expand Down
2 changes: 1 addition & 1 deletion src/hotspot/share/runtime/arguments.cpp
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Expand Up @@ -1836,7 +1836,7 @@ bool Arguments::check_vm_args_consistency() {

#ifndef _LP64
if (LockingMode == LM_LEGACY) {
FLAG_SET_CMDLINE(LockingMode, LM_LIGHTWEIGHT);
LockingMode = LM_LIGHTWEIGHT;
Comment on lines 1838 to +1839
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If we have prevented the locking mode from being set then surely we can never encounter this case?

// Self-forwarding in bit 3 of the mark-word conflicts
// with 4-byte-aligned stack-locks.
warning("Legacy locking not supported on this platform");
Expand Down
7 changes: 0 additions & 7 deletions src/hotspot/share/runtime/globals.hpp
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Expand Up @@ -1953,13 +1953,6 @@ const int ObjectAlignmentInBytes = 8;
"Mark all threads after a safepoint, and clear on a modify " \
"fence. Add cleanliness checks.") \
\
product(int, LockingMode, LM_LIGHTWEIGHT, \
"(Deprecated) Select locking mode: " \
"0: (Deprecated) monitors only (LM_MONITOR), " \
"1: (Deprecated) monitors & legacy stack-locking (LM_LEGACY), " \
"2: monitors & new lightweight locking (LM_LIGHTWEIGHT, default)") \
range(0, 2) \
\
product(bool, UseObjectMonitorTable, false, DIAGNOSTIC, \
"With Lightweight Locking mode, use a table to record inflated " \
"monitors rather than the first word of the object.") \
Expand Down
2 changes: 2 additions & 0 deletions src/hotspot/share/utilities/globalDefinitions.cpp
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Expand Up @@ -56,6 +56,8 @@ int LogMinObjAlignmentInBytes = -1;
// Oop encoding heap max
uint64_t OopEncodingHeapMax = 0;

int LockingMode = LM_LIGHTWEIGHT;
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const ?


// Something to help porters sleep at night

#ifdef ASSERT
Expand Down
2 changes: 2 additions & 0 deletions src/hotspot/share/utilities/globalDefinitions.hpp
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Expand Up @@ -1009,6 +1009,8 @@ enum LockingMode {
LM_LIGHTWEIGHT = 2
};

extern int LockingMode;
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const ?


//----------------------------------------------------------------------------------------------------
// Special constants for debugging

Expand Down
60 changes: 0 additions & 60 deletions src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/LockingMode.java
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This file was deleted.

33 changes: 11 additions & 22 deletions src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/Threads.java
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Expand Up @@ -222,29 +222,18 @@ private JavaThread owningThreadFromMonitor(Address o) {

public JavaThread owningThreadFromMonitor(ObjectMonitor monitor) {
if (monitor.isOwnedAnonymous()) {
if (VM.getVM().getCommandLineFlag("LockingMode").getInt() == LockingMode.getLightweight()) {
OopHandle object = monitor.object();
for (int i = 0; i < getNumberOfThreads(); i++) {
JavaThread thread = getJavaThreadAt(i);
if (thread.isLockOwned(object)) {
return thread;
}
}
// We should have found the owner, however, as the VM could be in any state, including the middle
// of performing GC, it is not always possible to do so. Just return null if we can't locate it.
System.out.println("Warning: We failed to find a thread that owns an anonymous lock. This is likely");
System.out.println("due to the JVM currently running a GC. Locking information may not be accurate.");
return null;
} else {
assert(VM.getVM().getCommandLineFlag("LockingMode").getInt() == LockingMode.getLegacy());
Address o = (Address)monitor.stackLocker();
for (int i = 0; i < getNumberOfThreads(); i++) {
JavaThread thread = getJavaThreadAt(i);
if (thread.isLockOwned(o))
return thread;
}
return null;
OopHandle object = monitor.object();
for (int i = 0; i < getNumberOfThreads(); i++) {
JavaThread thread = getJavaThreadAt(i);
if (thread.isLockOwned(object)) {
return thread;
}
}
// We should have found the owner, however, as the VM could be in any state, including the middle
// of performing GC, it is not always possible to do so. Just return null if we can't locate it.
System.out.println("Warning: We failed to find a thread that owns an anonymous lock. This is likely");
System.out.println("due to the JVM currently running a GC. Locking information may not be accurate.");
return null;
} else {
return owningThreadFromMonitor(monitor.owner());
}
Expand Down
5 changes: 1 addition & 4 deletions test/hotspot/jtreg/compiler/locks/TestSynchronizeWithEmptyBlock.java
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand All @@ -26,9 +26,6 @@
* @bug 8337660
* @summary Test that C2 does not remove blocks with BoxLock nodes that are
* otherwise empty.
* @run main/othervm -Xbatch -XX:LockingMode=1
* -XX:CompileOnly=compiler.locks.TestSynchronizeWithEmptyBlock::*
* compiler.locks.TestSynchronizeWithEmptyBlock
* @run main/othervm -Xbatch
* -XX:CompileOnly=compiler.locks.TestSynchronizeWithEmptyBlock::*
* compiler.locks.TestSynchronizeWithEmptyBlock
Expand Down
6 changes: 3 additions & 3 deletions test/hotspot/jtreg/gtest/LockStackGtests.java
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand All @@ -23,10 +23,10 @@
*/

/* @test
* @summary Run LockStack gtests with LockingMode=2
* @summary Run LockStack gtests
* @library /test/lib
* @modules java.base/jdk.internal.misc
* java.xml
* @requires vm.flagless
* @run main/native GTestWrapper --gtest_filter=LockStackTest* -XX:LockingMode=2
* @run main/native GTestWrapper --gtest_filter=LockStackTest*
*/
11 changes: 8 additions & 3 deletions test/hotspot/jtreg/runtime/Monitor/ConcurrentDeflation.java
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand All @@ -24,6 +24,7 @@
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.Platform;
import jdk.test.lib.process.ProcessTools;
import jdk.test.whitebox.WhiteBox;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
Expand All @@ -33,11 +34,14 @@
* @test
* @bug 8318757
* @summary Test concurrent monitor deflation by MonitorDeflationThread and thread dumping
* @library /test/lib
* @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedAsyncDeflationInterval=2000 -XX:LockingMode=0 ConcurrentDeflation
* @library /test/lib /
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedAsyncDeflationInterval=2000 -XX:+WhiteBoxAPI ConcurrentDeflation
*/

public class ConcurrentDeflation {
static final WhiteBox WB = WhiteBox.getWhiteBox();
public static final long TOTAL_RUN_TIME_NS = 10_000_000_000L;
public static Object[] monitors = new Object[1000];
public static int monitorCount;
Expand Down Expand Up @@ -73,6 +77,7 @@ static private void createMonitors() {
index = index++ % 1000;
monitors[index] = new Object();
synchronized (monitors[index]) {
WB.forceInflateMonitorLockedObject(monitors[index]);
monitorCount++;
}
}
Expand Down
90 changes: 0 additions & 90 deletions test/hotspot/jtreg/runtime/Monitor/StressWrapper_TestRecursiveLocking_36M.java
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Expand Up @@ -33,21 +33,6 @@
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=0
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I was wondering why these LockingMode=0 test cases were not setting VerifyHeavyMonitors instead, but I'm assuming the intent now is that we will only test that mode when it is set externally by the user (or in our case a particular test task definition)?

I also realized we can only test heavy monitors in tests where we explicitly control the monitor creation places and hence can call the WB method to force inflation. That obviously reduces the test coverage for that mode quite significantly - but perhaps that will be handled if in the future we implicitly reenable forced inflation and do away with the WB usage.

* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=1
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=2
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*/
Expand All @@ -63,21 +48,6 @@
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=0
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=1
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -Xint
* -XX:LockingMode=2
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*/
Expand All @@ -94,21 +64,6 @@
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=0
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=1
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=2
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*/
Expand All @@ -125,21 +80,6 @@
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=0
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=1
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:TieredStopAtLevel=1
* -XX:LockingMode=2
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*/
Expand All @@ -156,21 +96,6 @@
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:-EliminateNestedLocks
* -XX:LockingMode=0
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:-EliminateNestedLocks
* -XX:LockingMode=1
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:-EliminateNestedLocks
* -XX:LockingMode=2
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 1
*/
Expand All @@ -182,25 +107,10 @@
* @summary Tests recursive locking in C2 in alternate A and B mode.
* @library /testlibrary /test/lib
* @build jdk.test.whitebox.WhiteBox
*
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:LockingMode=0
* -XX:-EliminateNestedLocks
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:LockingMode=1
* -XX:-EliminateNestedLocks
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
*
* @run main/othervm/timeout=240 -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
* -XX:LockingMode=2
* -XX:-EliminateNestedLocks
* -Xms256m -Xmx256m
* TestRecursiveLocking 120 2
Expand Down
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