Phase 7.4: Snapshot-under-churn stress test (8 workers + 1 sampler, 5s) - #24
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- 8 worker threads tight-loop alloc/free at sizes [16,64,256,1024,16384] - 9th sampler thread snapshots SampledList every ~10ms for 5s - exercises H1-H4 dealloc hooks + lock-free SampledList under churn - TSan/ASan-clean by construction; sanitizer cmd lines documented inline - SNMALLOC_PROFILE=OFF path collapses to a "skipped" stub
jayakasadev
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Jun 11, 2026
- Adds two ubuntu-24.04 clang Debug matrix legs to the existing
ubuntu job in .github/workflows/main.yml so the heap-profiling
code paths exercised by perf-profile_stress and the func-profile_*
suite are run under ThreadSanitizer and AddressSanitizer.
- Both legs configure -DSNMALLOC_PROFILE=ON and the project's
existing SNMALLOC_SANITIZER cmake option (=thread / =address)
instead of raw CMAKE_CXX_FLAGS=-fsanitize=...; this is the
idiomatic mechanism already used by the existing "TSan + UBSan"
matrix entries (CMakeLists.txt:73-75, 580-606, 668-672) and
correctly wires -fsanitize through to test-target compile and
link lines plus the SNMALLOC_THREAD_SANITIZER_ENABLED define
the codebase guards on.
- The TSan leg installs libc++-dev and uses -stdlib=libc++ to
match the existing TSan + UBSan legs (libstdc++ on Ubuntu is
not TSan-instrumented). The ASan leg uses the default
libstdc++ runtime, which is ASan-compatible.
- Both legs pass `-R profile_` via test-extra-args so ctest runs
only the profile suite (perf-profile_stress-{fast,check} +
func-profile_*). This bounds sanitizer overhead within the
CI time budget while still exercising the new snapshot-under-
churn workload from PR #24.
- Local validation: configured + built + ran perf-profile_stress-fast
on darwin-arm64 with -DSNMALLOC_SANITIZER=address; the fast
variant ran ~5s under ASan with no diagnostics. TSan was not
validated locally because the macOS toolchain available here
does not ship a TSan-instrumented libc++; relying on the
GitHub ubuntu-24.04 runner for that leg as called out in the
ticket.
2 of 3 tasks
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Summary
Stress test for the lock-free SampledList + H1–H4 dealloc hooks under concurrent churn.
profile_e2e.cc/profile_integration.ccpattern) — needed to exercise H1–H4 since the defaultsnmalloc-testlibis built withNoClientMetaDataProvider.SamplerGlobals::list().snapshot()/debug_count()rather than the FFI thunk (rust.cc only compiles intosnmallocshim-rust, not into the testlib used by perf tests). Equivalence documented in the file's header.SNMALLOC_PROFILE=OFFthe body compiles toprintf("skipped")+ return 0.Measured this run: ~15M alloc/free pairs across 8 workers + ~417 snapshots; max live sample window ~16k (check) / ~1k (fast).
Test plan
perf-profile_stress-fast(SNMALLOC_PROFILE=ON)perf-profile_stress-check(SNMALLOC_PROFILE=ON)perf-profile_stress-fast(SNMALLOC_PROFILE=OFF, stub path)perf-profile_stress-check(SNMALLOC_PROFILE=OFF, stub path)