golang-mutex-tracer

Helps you debug slow lock/unlocks for golang sync Mutex/RWMutex

Example usage

Import with an alias for minimal impact.

Enable per lock:

import sync "github.com/RobinUS2/golang-mutex-tracer"

l := sync.Mutex{}
l.EnableTracer()
l.Lock()
l.Unlock()

Enable with customer settings per lock:

import sync "github.com/RobinUS2/golang-mutex-tracer"

l := sync.Mutex{}
l.EnableTracerWithOpts(sync.Opts{
    Threshold: 10 * time.Millisecond,
})
l.Lock()
l.Unlock()

Enable with customer name for lock:

import sync "github.com/RobinUS2/golang-mutex-tracer"

l := sync.Mutex{}
l.EnableTracerWithOpts(sync.Opts{
    Threshold: 10 * time.Millisecond,
    Id: "myLock",
})
l.Lock()
l.Unlock()

Enable for all locks (that use the import):

import sync "github.com/RobinUS2/golang-mutex-tracer"

l := sync.Mutex{}
sync.SetGlobalOpts(sync.Opts{
    Threshold: 100 * time.Millisecond,
    Enabled:   true,
})
l.Lock()
l.Unlock()

Example output

2019/02/20 13:32:04 testLock violation CRITICAL section took 23.477ms 23477000 (threshold 10ms)

Benchmark

Yes, there is performance impact. This is in the order of 1000 nanoseconds which is 0.001 milliseconds. However, the purpose of this project is to debug long blocked locks / contention, it should not be used continuously during production.

goos: darwin
goarch: amd64
BenchmarkRWNativeLock-8                          	 5000000	       381 ns/op
BenchmarkRWTracerLockDisabled-8                  	 5000000	       377 ns/op
BenchmarkRWTracerLockEnabled-8                   	 5000000	       385 ns/op
BenchmarkRWNativeLockWithConcurrency-8           	  200000	      6536 ns/op
BenchmarkRWTracerLockDisabledWithConcurrency-8   	  200000	      6504 ns/op
BenchmarkRWTracerLockEnabledWithConcurrency-8    	  200000	      6435 ns/op
BenchmarkNativeLock-8                            	100000000	        15.0 ns/op
BenchmarkTracerLockDisabled-8                    	 5000000	       366 ns/op
BenchmarkTracerLockEnabled-8                     	 5000000	       373 ns/op
BenchmarkNativeLockWithConcurrency-8             	 1000000	      1019 ns/op
BenchmarkTracerLockDisabledWithConcurrency-8     	  200000	      6431 ns/op
BenchmarkTracerLockEnabledWithConcurrency-8      	  200000	      6396 ns/op