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Optimize allocation hotspots

netty/netty
Based on 17 comments
Java

Identify and optimize object allocation in performance-critical paths by applying appropriate allocation strategies based on usage patterns. For frequently accessed objects, consider reusing instances rather than creating new ones. For short-lived objects in hot code paths, evaluate whether the JIT can optimize allocations away or if explicit object...

Performance Optimization Java

Reviewer Prompt

Identify and optimize object allocation in performance-critical paths by applying appropriate allocation strategies based on usage patterns. For frequently accessed objects, consider reusing instances rather than creating new ones. For short-lived objects in hot code paths, evaluate whether the JIT can optimize allocations away or if explicit object pooling/caching is needed.

For example, instead of creating new handler instances for each channel:

// Inefficient - creates new instance per channel
channel.pipeline().addLast(new MyHandler());

// Efficient - reuses single instance across channels
private static final MyHandler SHARED_HANDLER = new MyHandler();
// Add @Sharable annotation to handler class
channel.pipeline().addLast(SHARED_HANDLER);

For frequent operations, consider thread-local caching when appropriate:

// Cache event objects per thread for high-frequency operations
private static final ThreadLocal<MyEvent> EVENT_CACHE = 
    ThreadLocal.withInitial(MyEvent::new);

public void onHighFrequencyOperation() {
    MyEvent event = EVENT_CACHE.get();
    event.reset(); // Prepare for reuse
    // Use event...
}

When dealing with buffer management, ensure proper release and consider zero-copy approaches:

ByteBuf buffer = null;
try {
    buffer = allocator.directBuffer(size);
    // Use buffer...
} finally {
    if (buffer != null) {
        buffer.release(); // Ensure proper release
    }
}

For frequently used resource handles like file descriptors, consider caching and reuse:

// Instead of creating new pipes for each operation
if (pipe == null) {
    pipe = FileDescriptor.pipe();
}

Measure performance impact of allocation strategies with benchmarks before committing to complex optimization patterns, as JIT may already optimize simple allocation patterns in some cases.

17
Comments Analyzed
Java
Primary Language
Performance Optimization
Category

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