Make jemalloc profiling cover all threads when enabled#98232
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alexey-milovidov merged 5 commits intomasterfrom Mar 2, 2026
Merged
Make jemalloc profiling cover all threads when enabled#98232alexey-milovidov merged 5 commits intomasterfrom
alexey-milovidov merged 5 commits intomasterfrom
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When `jemalloc_enable_global_profiler` is set, the profiler must be activated before any threads are created — otherwise those threads won't be sampled. Move the `Jemalloc::setup` call to early in `BaseDaemon::initialize` (right after `loadConfiguration`) so that profiling is enabled before thread pools and background threads start. Guard `setup` with `std::call_once` so the later call from server settings is a safe no-op (with warnings if settings diverge). Extract default constants to `Jemalloc.h` and reuse them in `ServerSettings.cpp` and `BaseDaemon.cpp` to keep them in sync. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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antonio2368
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Feb 27, 2026
…USE_JEMALLOC guard The default constants (`default_enable_global_profiler`, etc.) are referenced by `ServerSettings.cpp` unconditionally, but were defined inside `#if USE_JEMALLOC`. Sanitizer builds don't use jemalloc, so the `Jemalloc` namespace was undefined, causing compilation failures. Move the constants before the guard so they are always available. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
azat
approved these changes
Feb 28, 2026
Add assertion before the warning in `Jemalloc::setup` to catch mismatches between server settings defaults and the manually defined config names in `BaseDaemon` early in debug builds. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The previous implementation used `std::call_once` which fired in the parent process during `BaseDaemon::initialize`. After the watchdog `fork`, jemalloc state (e.g. `background_thread`) resets in the child but the `once_flag` remains set, so the verification check saw a mismatch and fired `chassert`. Split `setup` and `verifySetup` into separate functions: - `setup` always applies settings (idempotent), called in `BaseDaemon::initialize` and re-applied after watchdog fork - `verifySetup` checks jemalloc state matches server settings, called from `Server::main` and `Keeper::main` Also extract config key names into constants in `Jemalloc.h` to keep them in sync between `BaseDaemon` and `ServerSettings`. https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=98232&sha=b69293471789706abde22ec86f33104dbfaf0382&name_0=PR&name_1=Stateless%20tests%20%28amd_debug%2C%20parallel%29 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Cherry pick #98232 to 26.2: Make jemalloc profiling cover all threads when enabled
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Backport #98232 to 26.2: Make jemalloc profiling cover all threads when enabled
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When
jemalloc_enable_global_profileris set, the profiler must be activated before any threads are created — otherwise those threads won't be sampled. Move theJemalloc::setupcall to early inBaseDaemon::initialize(right afterloadConfiguration) so that profiling is enabled before thread pools and background threads start.Guard
setupwithstd::call_onceso the later call from server settings is a safe no-op (with warnings if settings diverge).Extract default constants to
Jemalloc.hand reuse them inServerSettings.cppandBaseDaemon.cppto keep them in sync.Changelog category (leave one):
It seems we do miss some of the threads, most problematic the async logger thread.
Documentation entry for user-facing changes