On Tue, 4 Feb 2025 00:59:57 GMT, Shaojin Wen <s...@openjdk.org> wrote:
>> The following code can reproduce the problem, writing out of bounds causes
>> JVM Crash
>>
>>
>> StringBuilder buf = new StringBuilder();
>> buf.append('中');
>>
>> final CountDownLatch latch = new CountDownLatch(10);
>> Runnable r = () -> {
>> for (int i = 0; i < 10000; i++) {
>> buf.setLength(0);
>> buf.trimToSize();
>> buf.append(123456789);
>> }
>> latch.countDown();
>> };
>> Thread[] threads = new Thread[10];
>> for (int i = 0; i < threads.length; i++) {
>> threads[i] = new Thread(r);
>> }
>> for (Thread t : threads) {
>> t.start();
>> }
>> latch.await();
>> }
>>
>>
>> This problem can be avoided by using the value of ensureCapacityInternal
>> directly.
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> skip coder change
> ```java
> StringBuilder buf = new StringBuilder();
> buf.append('中');
>
> final CountDownLatch latch = new CountDownLatch(10);
> Runnable r = () -> {
> for (int i = 0; i < 10000; i++) {
> buf.setLength(0);
> buf.trimToSize();
> buf.append(123456789);
> }
> latch.countDown();
> };
> Thread[] threads = new Thread[10];
> for (int i = 0; i < threads.length; i++) {
> threads[i] = new Thread(r);
> }
> for (Thread t : threads) {
> t.start();
> }
> latch.await();
> ```
Will cause the JVM to exit directly, the error message is as follows
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGBUS (0xa) at pc=0x0000000103b9d23c, pid=23348, tid=33539
#
# JRE version: OpenJDK Runtime Environment (25.0) (build
25-internal-adhoc.wenshao.jdkx)
# Java VM: OpenJDK 64-Bit Server VM (25-internal-adhoc.wenshao.jdkx, mixed
mode, tiered, compressed oops, compressed class ptrs, g1 gc, bsd-aarch64)
# Problematic frame:
# [thread 41731 also had an error]
V [libjvm.dylib+0x41523c]
G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr, oopDesc*,
markWord)+0x64
#
# No core dump will be written. Core dumps have been disabled. To enable core
dumping, try "ulimit -c unlimited" before starting Java again
#
[thread 39683 also had an error]
# An error report file with more information is saved as:
# /Users/wenshao/Work/git/jdk_mico_bench/hs_err_pid23348.log
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
-------------
PR Comment: https://git.openjdk.org/jdk/pull/23427#issuecomment-2634006503
