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 [v5]
Guanqiang Han
ghan at openjdk.org
Fri Jan 16 01:02:52 UTC 2026
> 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 incrementally with one additional commit since the last revision:
Polish regression test and move it to runtime/os
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/29212/files
- new: https://git.openjdk.org/jdk/pull/29212/files/83d58fb4..c821a55d
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=29212&range=04
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=29212&range=03-04
Stats: 4 lines in 1 file changed: 0 ins; 2 del; 2 mod
Patch: https://git.openjdk.org/jdk/pull/29212.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/29212/head:pull/29212
PR: https://git.openjdk.org/jdk/pull/29212
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