fix(profiling): re-initialise string tables post-fork by KowalskiThomas · Pull Request #18063 · DataDog/dd-trace-py

KowalskiThomas · 2026-05-13T07:08:10Z

Description

This PR ensures we clear the string tables post-fork. This is meant to address a crash happening on (at least) 4.8.0rc5.

Error UnixSignal: Process terminated with SEGV_MAPERR (SIGSEGV)
#0   0x0000000000000000 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804)
#1   0x000073afd44ec124 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804)
#2   0x000073afd44ec124 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node(unsigned long, unsigned long const&, unsigned long) const [clone .constprop.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1580)
#3   0x000073afd44ece4b std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_node(unsigned long, unsigned long const&, unsigned long) const [clone .isra.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:694)
#4   0x0000000000000000 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455)
#5   0x0000000000000000 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920)
#6   0x000073afd44e4e61 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455)
#7   0x000073afd44e4e61 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920)
#8   0x000073afd44e4e61 StringTable::key(_object*, StringTag) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/strings.cc:58)
#9   0x000073afd44e517f Frame::create(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:24)
#10  0x000073afd44e5436 Frame::get(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:214)
#11  0x000073afd44e55b1 Frame::read(EchionSampler&, _PyInterpreterFrame*, _PyInterpreterFrame**) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:153)
#12  0x000073afd44e56c0 unwind_frame(EchionSampler&, _object*, FrameStack&, unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:56)
#13  0x000073afd44e5859 unwind_python_stack(EchionSampler&, _ts*, FrameStack&) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:103)
#14  0x000073afd44e7bbf ThreadInfo::unwind(EchionSampler&, _ts*) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:15)
#15  0x0000000000000000 __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979)
#16  0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839)
#17  0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008)
#18  0x000073afd44eb2eb __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979)
#19  0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839)
#20  0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008)
#21  0x000073afd44eb2eb ThreadInfo::sample(EchionSampler&, _ts*, long) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:698)
#22  0x000073afd44eb789 Datadog::Sampler::sampling_thread(unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:287)
#23  0x000073afd44ebad0 call_sampling_thread(void*) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:45)
#24  0x000073afdf06bac3 start_thread (nptl/nptl/pthread_create.c:442)
#25  0x000073afdf0fd8d0 __clone3

cit-pr-commenter-54b7da · 2026-05-13T07:09:25Z

Codeowners resolved as

ddtrace/internal/datadog/profiling/stack/echion/echion/strings.h        @DataDog/profiling-python
ddtrace/internal/datadog/profiling/stack/src/sampler.cpp                @DataDog/profiling-python
releasenotes/notes/profiling-fix-post-fork-crash-string-table-2b3c3c6749b2c102.yaml  @DataDog/apm-python

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emmettbutler

Oh cool. I wonder if the same logic is applied to the string table that underlies the TraceWriter.

KowalskiThomas · 2026-05-15T08:34:39Z

@emmettbutler From what I know, I don't think so. We only need to do that in the Profiling Sampling Thread because it's a native Thread (not a PeriodicThread nor Python-owned Thread) that we don't stop at fork, which means post-fork everything that Thread touches without synchronisation can be in any kind of weird state. If the Trace Writer Thread is a Periodic Thread (like for example the Profiling Scheduler / Uploader Thread is), then I believe now we definitely stop/join those Threads before fork which means they can't corrupt anything from suddenly stopping to exist at fork. If it's not a PeriodicThread, though, things may be different (but I'd be surprised, as I haven't seen any crashes that would indicate so).

datadog-datadog-prod-us1 · 2026-05-15T15:04:32Z

Tests

✨ Fix all issues with BitsAI

⚠️ Warnings

🚦 8 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-py | build linux serverless: [arm64, cp315-cp315, v113741589-d2b8243-musllinux_1_2_aarch64, 1]

🔧 Fix in code (Fix with Cursor).
AssertionError: Failed with DD_IAST_ENABLED=0: 1 during native module load test.

DataDog/apm-reliability/dd-trace-py | build linux serverless: [amd64, cp315-cp315, v113741238-d2b8243-manylinux2014_x86_64, 1]

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Job failed to schedule due to insufficient resources and node affinity issues across multiple nodes.

DataDog/apm-reliability/dd-trace-py | build linux serverless: [arm64, cp315-cp315, v113741357-d2b8243-manylinux2014_aarch64, 1]

🔄 Retry job. This looks flaky and may succeed on retry.
Failed to create pod sandbox: unable to allocate IP via local cilium agent: no IPs currently available on the node.

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KowalskiThomas · 2026-05-21T12:17:37Z

/merge -f --reason "microbenchmarks broken for unrelated reason"

gh-worker-devflow-routing-ef8351 · 2026-05-21T12:17:42Z

View all feedbacks in Devflow UI.

2026-05-21 12:17:42 UTC ℹ️ Start processing command /merge -f --reason "microbenchmarks broken for unrelated reason"

2026-05-21 12:17:47 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in main is approximately 0s (p90).

2026-05-21 12:17:59 UTC ℹ️ MergeQueue: This merge request was merged

Warning

This change was merged without running any pre merge CI checks

Reason: microbenchmarks broken for unrelated reason

…s to CI **Deterministic unit test** (`test_ddup_atfork_handler_registered_before_stack_sampler`): - Mocks `ddup.start` and `StackCollector._init` to record their call order during profiler startup, then asserts ddup was first. - POSIX guarantees FIFO ordering for post-fork child handlers, so whichever component calls pthread_atfork first gets its child handler run first. ddup must run first to rebuild profile state before the stack sampler clears and re-registers threads. - Catches the regression deterministically without needing timing luck or fork() calls — a swap of the init order in profiler.py fails immediately. - Regression guard for PRs #17183/#17042/#18063. **CI: stress-ng CPU saturation + 20 iterations**: - Runs `stress-ng --cpu $(nproc)` in the background during the fork loop to saturate all CPUs and widen the pthread_atfork timing race window — the same load profile that makes the bug manifest in production Gunicorn/gthread. - Increased iterations from 10 to 20 to give more chances to surface the race. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

github-actions · 2026-06-09T08:48:30Z

This change is marked for backport to 4.8 and it does not conflict with that branch.
The command used to test backporting was

git checkout 4.8 && git cherry-pick -x --mainline 1 f1f69015b6bf5f5cd0caf30cb9132b121565edcf

## Description This PR ensures we clear the string tables post-fork. This is meant to address a crash happening on (at least) 4.8.0rc5. ``` Error UnixSignal: Process terminated with SEGV_MAPERR (SIGSEGV) #0 0x0000000000000000 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804) #1 0x000073afd44ec124 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804) #2 0x000073afd44ec124 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node(unsigned long, unsigned long const&, unsigned long) const [clone .constprop.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1580) #3 0x000073afd44ece4b std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_node(unsigned long, unsigned long const&, unsigned long) const [clone .isra.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:694) #4 0x0000000000000000 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455) #5 0x0000000000000000 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920) #6 0x000073afd44e4e61 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455) #7 0x000073afd44e4e61 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920) #8 0x000073afd44e4e61 StringTable::key(_object*, StringTag) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/strings.cc:58) #9 0x000073afd44e517f Frame::create(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:24) #10 0x000073afd44e5436 Frame::get(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:214) #11 0x000073afd44e55b1 Frame::read(EchionSampler&, _PyInterpreterFrame*, _PyInterpreterFrame**) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:153) #12 0x000073afd44e56c0 unwind_frame(EchionSampler&, _object*, FrameStack&, unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:56) #13 0x000073afd44e5859 unwind_python_stack(EchionSampler&, _ts*, FrameStack&) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:103) #14 0x000073afd44e7bbf ThreadInfo::unwind(EchionSampler&, _ts*) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:15) #15 0x0000000000000000 __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979) #16 0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839) #17 0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008) #18 0x000073afd44eb2eb __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979) #19 0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839) #20 0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008) #21 0x000073afd44eb2eb ThreadInfo::sample(EchionSampler&, _ts*, long) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:698) #22 0x000073afd44eb789 Datadog::Sampler::sampling_thread(unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:287) #23 0x000073afd44ebad0 call_sampling_thread(void*) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:45) #24 0x000073afdf06bac3 start_thread (nptl/nptl/pthread_create.c:442) #25 0x000073afdf0fd8d0 __clone3 ``` Co-authored-by: thomas.kowalski <thomas.kowalski@datadoghq.com> (cherry picked from commit f1f6901) Co-authored-by: Thomas Kowalski <thomas.kowalski@datadoghq.com>

…18531) Backport #18063 to 4.8 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Thomas Kowalski <thomas.kowalski@datadoghq.com>

github-actions · 2026-06-09T14:47:31Z

This change is marked for backport to 4.9 and it does not conflict with that branch.
The command used to test backporting was

git checkout 4.9 && git cherry-pick -x --mainline 1 f1f69015b6bf5f5cd0caf30cb9132b121565edcf

github-actions · 2026-06-09T14:47:32Z

This change is marked for backport to 4.10 and it does not conflict with that branch.
The command used to test backporting was

git checkout 4.10 && git cherry-pick -x --mainline 1 f1f69015b6bf5f5cd0caf30cb9132b121565edcf

## Description This PR ensures we clear the string tables post-fork. This is meant to address a crash happening on (at least) 4.8.0rc5. ``` Error UnixSignal: Process terminated with SEGV_MAPERR (SIGSEGV) #0 0x0000000000000000 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804) #1 0x000073afd44ec124 std::__detail::_Hashtable_base<unsigned long, std::pair<unsigned long const, std::string>, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<false, false, true> >::_M_equals(unsigned long const&, unsigned long, std::__detail::_Hash_node<std::pair<unsigned long const, std::string>, false>*) const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable_policy.h:1804) #2 0x000073afd44ec124 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node(unsigned long, unsigned long const&, unsigned long) const [clone .constprop.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1580) #3 0x000073afd44ece4b std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_node(unsigned long, unsigned long const&, unsigned long) const [clone .isra.0] (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:694) #4 0x0000000000000000 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455) #5 0x0000000000000000 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920) #6 0x000073afd44e4e61 std::_Hashtable<unsigned long, std::pair<unsigned long const, std::string>, std::allocator<std::pair<unsigned long const, std::string> >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/hashtable.h:1455) #7 0x000073afd44e4e61 std::unordered_map<unsigned long, std::string, std::hash<unsigned long>, std::equal_to<unsigned long>, std::allocator<std::pair<unsigned long const, std::string> > >::find(unsigned long const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/unordered_map.h:920) #8 0x000073afd44e4e61 StringTable::key(_object*, StringTag) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/strings.cc:58) #9 0x000073afd44e517f Frame::create(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:24) #10 0x000073afd44e5436 Frame::get(EchionSampler&, PyCodeObject*, int) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:214) #11 0x000073afd44e55b1 Frame::read(EchionSampler&, _PyInterpreterFrame*, _PyInterpreterFrame**) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/frame.cc:153) #12 0x000073afd44e56c0 unwind_frame(EchionSampler&, _object*, FrameStack&, unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:56) #13 0x000073afd44e5859 unwind_python_stack(EchionSampler&, _ts*, FrameStack&) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/stacks.cc:103) #14 0x000073afd44e7bbf ThreadInfo::unwind(EchionSampler&, _ts*) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:15) #15 0x0000000000000000 __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979) #16 0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839) #17 0x0000000000000000 std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008) #18 0x000073afd44eb2eb __gnu_cxx::__normal_iterator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const*, std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > > >::__normal_iterator(std::unique_ptr<StackInfo, std::default_delete<StackInfo> > const* const&) (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_iterator.h:979) #19 0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::end() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:839) #20 0x000073afd44eb2eb std::vector<std::unique_ptr<StackInfo, std::default_delete<StackInfo> >, std::allocator<std::unique_ptr<StackInfo, std::default_delete<StackInfo> > > >::empty() const (/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/stl_vector.h:1008) #21 0x000073afd44eb2eb ThreadInfo::sample(EchionSampler&, _ts*, long) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/echion/threads.cc:698) #22 0x000073afd44eb789 Datadog::Sampler::sampling_thread(unsigned long) [clone .localalias] (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:287) #23 0x000073afd44ebad0 call_sampling_thread(void*) (/go/src/github.com/DataDog/apm-reliability/dd-trace-py/ddtrace/internal/datadog/profiling/stack/src/sampler.cpp:45) #24 0x000073afdf06bac3 start_thread (nptl/nptl/pthread_create.c:442) #25 0x000073afdf0fd8d0 __clone3 ``` Co-authored-by: thomas.kowalski <thomas.kowalski@datadoghq.com> (cherry picked from commit f1f6901) Co-authored-by: Thomas Kowalski <thomas.kowalski@datadoghq.com>

KowalskiThomas added Profiling Continous Profling identified-by:crashtracking Identified by Crash Tracking labels May 13, 2026

KowalskiThomas marked this pull request as ready for review May 13, 2026 08:41

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KowalskiThomas requested review from mabdinur and taegyunkim May 13, 2026 08:41

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Comment thread ddtrace/internal/datadog/profiling/stack/echion/echion/strings.h Outdated

KowalskiThomas force-pushed the kowalski/fix-profiling-clear-string-tables-post-fork branch 2 times, most recently from b37f328 to 17cbcbc Compare May 13, 2026 12:33

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KowalskiThomas changed the title ~~fix(profiling): clear string tables post-fork~~ fix(profiling): re-initialise string tables post-fork May 15, 2026

KowalskiThomas force-pushed the kowalski/fix-profiling-clear-string-tables-post-fork branch from 17cbcbc to 512674c Compare May 15, 2026 14:54

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Comment thread ddtrace/internal/datadog/profiling/stack/echion/echion/strings.h

KowalskiThomas force-pushed the kowalski/fix-profiling-clear-string-tables-post-fork branch 2 times, most recently from 4450da7 to 74cd85b Compare May 20, 2026 13:54

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Comment thread releasenotes/notes/profiling-fix-post-fork-crash-string-table-2b3c3c6749b2c102.yaml

fix(profiling): clear string tables post-fork

d9381a6

KowalskiThomas force-pushed the kowalski/fix-profiling-clear-string-tables-post-fork branch from 74cd85b to d9381a6 Compare May 21, 2026 07:59

gh-worker-dd-mergequeue-cf854d Bot merged commit f1f6901 into main May 21, 2026
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vlad-scherbich mentioned this pull request Jun 8, 2026

test(profiling): regression test for fork+gthread worker thread visibility #18507

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KowalskiThomas added the backport 4.8 label Jun 9, 2026

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fix(profiling): re-initialise string tables post-fork [backport 4.8] #18531

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fix(profiling): re-initialise string tables post-fork [backport 4.9] #18544

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fix(profiling): re-initialise string tables post-fork#18063

fix(profiling): re-initialise string tables post-fork#18063
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