Add more visibility to catch sleeping barber #21742
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goedderz
reviewed
Apr 30, 2025
arangod/Aql/ExecutionBlockImpl.tpp
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| ExecutionBlockImpl<Executor>::~ExecutionBlockImpl() { | ||
| // Double use diagnostics: | ||
| uint64_t userCount = _numberOfUsers.fetch_add(1); | ||
| if (userCount > 0) { | ||
| LOG_TOPIC("52637", WARN, Logger::QUERIES) | ||
| << "ALERT: Double use of ExecutionBlock detected, stacktrace:"; | ||
| CrashHandler::logBacktrace(); | ||
| _logStacktrace.store(true, std::memory_order_relaxed); | ||
| } | ||
| auto guard = scopeGuard([&]() noexcept { | ||
| uint64_t userCount = _numberOfUsers.fetch_sub(1); | ||
| if (_logStacktrace.load(std::memory_order_relaxed)) { | ||
| LOG_TOPIC("52638", WARN, Logger::QUERIES) | ||
| << "ALERT: Found _logStacktrace:"; | ||
| CrashHandler::logBacktrace(); | ||
| if (userCount == 0) { | ||
| _logStacktrace.store(false, std::memory_order_relaxed); | ||
| } | ||
| } | ||
| 8000 | }); | |
| stopAsyncTasks(); |
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We must also do the user-accounting when calling stopAsyncTasks directly from ~ExecutionEngine (before ~ExecutionBlockImpl destructors are executed).
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Totally right, will fix.
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Moved user checking to stopAsyncTasks().
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For our hunt of a sleeper we add further diagnosis:
PrefetchTask::waitForgets a loop with a timeout andmore logging if the timeout occurs.
thread concurrently w.r.t.
execute()and the destructor.concurrently.
Scope & Purpose
(Please describe the changes in this PR for reviewers, motivation, rationale - mandatory)
Checklist