multiple tests (api.rseq, api.startstop, burst_threads, synch_attach) failed with "Failed to synchronize" on detach

[prasun3]

Describe the bug

Seen in #5907

in event_post_attach
in event_pre_detach
<Application /home/pratn/dynamorio-latest/build-x86-32/suite/tests/bin/api.startstop (124291). Failed to synchronize with all threads when detaching.>

To Reproduce
Run suite/tests/bin/api.startstop

Expected behavior

Screenshots or Pasted Text

Versions

• What version of DynamoRIO are you using?
• Does the latest build from https://github.com/DynamoRIO/dynamorio/releases solve the problem?
• What operating system version are you running on? ("Windows 10" is not sufficient: give the release number.)
  • Linux
• Is your application 32-bit or 64-bit?
  • 32-bit

Additional context

[derekbruening]

There are other issues on startstop test failures (#4604, #2093, #2246) so I added the precise failure reason to the title here.

[derekbruening]

Happened in burst_threads test: https://github.com/DynamoRIO/dynamorio/actions/runs/16353704551/job/46206684643

[derekbruening]

I merged #6185 here.

[edeiana]

code_api|tool.drcacheoff.burst_threads in ci x86-32 failed with:

Failed to synchronize with all threads when detaching.

at 004151938c2a2a8133295a79415aa8268b143616 (in PR #7556) after merging with master.
The test passed on the second try.

From the ci log:

2025-07-23T03:17:18.3161649Z       Test #374: code_api|tool.drcacheoff.burst_threads ...........................***Failed   58.64 sec
2025-07-23T03:17:18.3162675Z Running |/opt/hostedtoolcache/cmake/3.19.7/x64/cmake-3.19.7-Linux-x86_64/bin/cmake;-E;remove_directory /home/runner/work/dynamorio/dynamorio/build_debug-internal-32/suite/tests/drmemtrace.tool.drcacheoff.burst_threads.26729.1754.dir|
2025-07-23T03:17:18.3164282Z Running |/opt/hostedtoolcache/cmake/3.19.7/x64/cmake-3.19.7-Linux-x86_64/bin/cmake;-E;remove_directory /home/runner/work/dynamorio/dynamorio/build_debug-internal-32/suite/tests/drmemtrace.tool.drcacheoff.burst_threads.26729.3740.dir|
2025-07-23T03:17:18.3165755Z Running |/opt/hostedtoolcache/cmake/3.19.7/x64/cmake-3.19.7-Linux-x86_64/bin/cmake;-E;remove_directory /home/runner/work/dynamorio/dynamorio/build_debug-internal-32/suite/tests/drmemtrace.tool.drcacheoff.burst_threads.26729.4652.dir|
2025-07-23T03:17:18.3167449Z Running |/opt/hostedtoolcache/cmake/3.19.7/x64/cmake-3.19.7-Linux-x86_64/bin/cmake;-E;remove_directory /home/runner/work/dynamorio/dynamorio/build_debug-internal-32/suite/tests/drmemtrace.tool.drcacheoff.burst_threads.26729.5689.dir|
2025-07-23T03:17:18.3168586Z Running cmd |/home/runner/work/dynamorio/dynamorio/build_debug-internal-32/clients/bin32/tool.drcacheoff.burst_threads|
2025-07-23T03:17:18.3169284Z CMake Error at /home/runner/work/dynamorio/dynamorio/suite/tests/process_cmdline.cmake:109 (message):
2025-07-23T03:17:18.3169720Z   *** cmd failed (40): pre-DR init
2025-07-23T03:17:18.3169866Z 
2025-07-23T03:17:18.3169929Z   pre-DR start
2025-07-23T03:17:18.3170034Z 
2025-07-23T03:17:18.3170095Z   pre-DR detach
2025-07-23T03:17:18.3170192Z 
2025-07-23T03:17:18.3170328Z   pre-DR init
2025-07-23T03:17:18.3170430Z 
2025-07-23T03:17:18.3170490Z   pre-DR start
2025-07-23T03:17:18.3170582Z 
2025-07-23T03:17:18.3170648Z   <Application
2025-07-23T03:17:18.3171043Z   /home/runner/work/dynamorio/dynamorio/build_debug-internal-32/clients/bin32/tool.drcacheoff.burst_threads
2025-07-23T03:17:18.3171567Z   (31477).  Failed to synchronize with all threads when detaching.>
2025-07-23T03:17:18.3171883Z 
2025-07-23T03:17:18.3171939Z   ***
2025-07-23T03:17:18.3172023Z 
2025-07-23T03:17:18.3172100Z Call Stack (most recent call first):
2025-07-23T03:17:18.3172479Z   /home/runner/work/dynamorio/dynamorio/suite/tests/runmulti.cmake:57 (process_cmdline)

[abhinav92003]

tool.drcacheoff.burst_threads failed on x86-32 again (https://github.com/DynamoRIO/dynamorio/actions/runs/16638503332/attempts/1) in the master merge for 0a9748a

[derekbruening]

The new synch_attach test, which uses the burst_threads executable, hit this: see #7621 (comment)