Ensure proper synchronization mechanisms to prevent deadlocks and race conditions in concurrent code. When designing thread-safe components, carefully consider lock ordering, avoid nested synchronization blocks that could cause deadlocks, and make mutable shared state thread-safe. Key practices: 1. **Avoid nested locks**: Don't call methods that acquire locks while holding another lock, as this can lead to deadlock scenarios 2. **Make shared mutable state thread-safe**: Use proper synchronization for fields accessed by multiple threads 3. **Document concurrency assumptions**: Clearly specify which methods are thread-safe and which require external synchronization 4. **Use appropriate synchronization primitives**: Choose between synchronized blocks, ReentrantLock, or other mechanisms based on the specific use case Example of problematic code: ```java // Dangerous: calling acquisitionLockTimeoutTask.run() within synchronized block synchronized void completeStateTransition(boolean commit) { // ... other operations if (acquisitionLockTimeoutTask.hasExpired()) acquisitionLockTimeoutTask.run(); // Could cause deadlock } // Dangerous: mutable public field accessed by multiple threads public ClientInformation clientInformation; // Not thread-safe ``` Example of safer approach: ```java // Better: avoid nested locks, handle synchronization explicitly synchronized void completeStateTransition(boolean commit) { // ... state transition logic // Schedule task execution outside of synchronized block } // Better: provide controlled access to mutable state private volatile ClientInformation clientInformation; public synchronized void updateClientInformation(ClientInformation info) { // Controlled update with proper synchronization } ``` Always analyze the potential for deadlock when acquiring multiple locks and consider whether operations can be restructured to avoid nested synchronization.