Anti-patterns related to thread synchronization that can lead to performance problems.
Synchronization Issues Overview
Proper thread synchronization is essential for ensuring data consistency in concurrent applications. However, excessive or improper synchronization can lead to significant performance issues, including contention, deadlocks, and reduced throughput.
Common synchronization-related performance issues include:
This guide covers common anti-patterns related to thread synchronization, along with best practices for optimizing concurrent performance across different programming languages and application types.
Excessive Synchronization
Excessive synchronization, such as synchronizing entire methods or using coarse-grained locks, can lead to thread contention and reduced throughput, especially when the synchronized block contains slow operations like I/O.
To minimize synchronization overhead:
Improper Lock Granularity
Improper lock granularity, such as using a single lock for an entire collection instead of individual locks for each element, can lead to unnecessary contention and reduced parallelism.
To optimize lock granularity:
Unnecessary Thread Synchronization
Unnecessary thread synchronization, such as synchronizing read-only data or using synchronization when thread-safety isn’t required, adds overhead without providing any benefit.
To avoid unnecessary synchronization:
Inefficient Reader-Writer Patterns
Inefficient reader-writer patterns, such as using exclusive locks for read-heavy workloads, can lead to unnecessary contention and reduced throughput.
To optimize reader-writer patterns:
Inefficient Thread Pool Configuration
Inefficient thread pool configuration, such as creating too many threads or using inappropriate queue sizes, can lead to resource exhaustion, increased context switching, and reduced performance.
To optimize thread pool configuration:
Deadlock-Prone Lock Ordering
Deadlock-prone lock ordering, such as acquiring locks in an inconsistent order across different threads, can lead to deadlocks where threads are permanently blocked waiting for locks held by each other.
To prevent deadlocks through proper lock ordering:
Busy Waiting
Busy waiting, or spinning, is a synchronization anti-pattern where a thread continuously checks a condition without releasing the CPU, wasting computational resources and potentially causing performance issues.
To avoid busy waiting:
Synchronized Method Cascades
Synchronized method cascades occur when synchronized methods call other synchronized methods, potentially leading to nested locks, increased contention, and reduced concurrency.
To avoid synchronized method cascades:
Contended Locks
Contended locks occur when many threads compete for the same lock, leading to significant thread blocking, context switching overhead, and reduced throughput.
To reduce lock contention:
Synchronization Best Practices Checklist
Proper thread synchronization is a balancing act between ensuring data consistency and maintaining good performance. By following best practices, you can minimize synchronization overhead while still ensuring thread safety.
Key principles for efficient synchronization: