RFR: 8375125: assert(false) failed: "Attempting to acquire lock NativeHeapTrimmer_lock/nosafepoint out of order with lock ConcurrentHashTableResize_lock/nosafepoint-2 -- possible deadlock" when using native heap trimmer [v6]

[David Holmes]

On Fri, 16 Jan 2026 03:33:19 GMT, Guanqiang Han <ghan at openjdk.org> wrote:

>> Please review this change. Thanks!
>> 
>> **Description:**
>> 
>> When -XX:TrimNativeHeapInterval=non-zero is enabled, running Test6892265 can trigger a VM abort due to a detected deadlock (or lock-order issue) during SymbolTable cleanup.
>> SymbolTable::clean_dead_entries() calls BulkDeleteTask::prepare(), which may take ConcurrentHashTableResize_lock (nosafepoint-2). 
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/classfile/symbolTable.cpp#L765-L769
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/utilities/concurrentHashTableTasks.inline.hpp#L159-L160
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/utilities/concurrentHashTable.inline.hpp#L307-L310
>> 
>> 
>> It then constructs a NativeHeapTrimmer::SuspendMark, which may take NativeHeapTrimmer_lock (nosafepoint). This can invert the lock order with the trimmer thread.
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/classfile/symbolTable.cpp#L773
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/runtime/trimNativeHeap.hpp#L56-L59
>> https://github.com/openjdk/jdk/blob/0d19d91b44e5232dbd99d34dcdf6500f892e3048/src/hotspot/share/runtime/trimNativeHeap.cpp#L177-L181
>> 
>> **Fix:**
>> 
>> Move NativeHeapTrimmer::SuspendMark to the beginning of SymbolTable::clean_dead_entries() before BulkDeleteTask::prepare() to enforce a consistent lock order
>> 
>> **Test:**
>> 
>> GHA
>
> Guanqiang Han has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:
> 
>  - adjust gc parameter
>  - Merge remote-tracking branch 'upstream/master' into 8375125
>  - Polish regression test and move it to runtime/os
>  - remove Whitespace
>  - correct copyright year
>  - add regression test and fix an error in stringTable
>  - Merge remote-tracking branch 'upstream/master' into 8375125
>  - fix 8375125

Nothing further from me. Thanks

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29212#pullrequestreview-3668815023