java concurrency_error ai_generated true

Found one Java-level deadlock

ID: java/deadlock-detected

Also available as: JSON · Markdown
75%Fix Rate
82%Confidence
55Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
17 active — — —

Root Cause

Two or more threads are each holding a lock while waiting to acquire a lock held by another, creating a circular dependency that prevents any of them from progressing. Detected by JVM thread dump analysis or JMX MXBeans.

generic

Workarounds

  1. 88% success Establish a consistent global lock ordering and refactor code to always acquire locks in the same order 
    1. Take a thread dump (jstack <pid> or kill -3 <pid>) to identify the deadlocked threads and locks. 2. Map out the lock acquisition order of each thread. 3. Define a global ordering for all locks (e.g., by object hash code or a logical hierarchy). 4. Refactor all code paths to acquire locks in that order. 5. Use java.util.concurrent.locks.ReentrantLock with tryLock(timeout) as a safety net.
  2. 85% success Replace synchronized blocks with java.util.concurrent data structures and Lock objects 
    1. Replace synchronized HashMap with ConcurrentHashMap. 2. Replace synchronized blocks with ReentrantLock.tryLock(timeout) which fails gracefully instead of deadlocking. 3. Use higher-level concurrency utilities (CompletableFuture, ExecutorService) instead of manual lock management. 4. Consider lock-free algorithms where possible.

Dead Ends

Common approaches that don't work:

  1. Increasing thread pool size to work around the deadlock 90% fail

    Adding more threads does not resolve a deadlock — the circular lock dependency remains. New threads may also deadlock on the same resources, making the situation worse.

  2. Adding synchronized blocks around existing synchronized blocks to force ordering 75% fail

    Adding more synchronization without careful analysis often creates new deadlock opportunities. Nested synchronization increases the chance of circular dependencies.

Error Chain

Leads to:
Preceded by:
Frequently confused with: