#33856 emit warning when thread pool task scheduler is unable to meet task delay #35611
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ThreadPoolTaskScheduler now monitors scheduled tasks and logs warnings when tasks are delayed due to insufficient pool size. This helps diagnose thread starvation issues and suggests increasing pool size or enabling virtual threads. Closes spring-projectsgh-33856
Address production blockers in delay monitoring feature from spring-projects#33856: - Fix race conditions in circuit breaker using AtomicReference with CAS - Fix memory leak in sliding window rate limiter with bounded queue - Make stopDelayMonitor() lock-free to prevent deadlock - Add bounds check for warningRateLimitMs (max 24 hours) - Fix resetWarningRateLimit() to clear sliding window queue Add 7 concurrency tests covering race conditions, memory leaks, and deadlock scenarios. All 24 tests pass (100%). Implementation now uses lock-free algorithms throughout for thread safety without performance degradation. See spring-projectsgh-33856
spring-projects-issues
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status: waiting-for-triage
sbrannen
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in: core
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Add delay monitoring to ThreadPoolTaskScheduler
Fixes #33856
Problem
ThreadPoolTaskSchedulerwith default pool size of 1 silently suffers from thread starvation when multiple tasks are scheduled, leading to production issues that are hard to diagnose.Solution
Added automatic delay monitoring that:
Key Features
Example Warning
WARN o.s.s.c.ThreadPoolTaskScheduler - 5 scheduled tasks are delayed
(max delay: 1488ms) due to thread pool exhaustion. Pool size: 1,
Active threads: 1, Queue size: 5. Consider increasing the pool size
via ThreadPoolTaskScheduler.setPoolSize() or
spring.task.scheduling.pool.size property.
Testing
Verified on production-like workload with demo application. All edge cases covered including concurrent modifications, circuit breaker transitions, and error recovery.