To judge that goroutine leaks, you can observe the increase in the number of numbers through runtime.NumGoroutine() or use pprof to view stack information; common scenarios include: 1. Send to the closed channel or receive from the non-write channel, causing blockage; 2. Forgot to close the channel, causing the consumer to be unable to exit; 3. Not canceling the context causes task suspension; the recommended practices are to use select default or context to control the life cycle, close the channel in time and set a timeout, and use defer cancel() to release the context; the testing tools, pprof, and leaktest libraries can be used to assist in detection; summary techniques include clarifying the exit conditions, using the reasonable use of context and channel, and adding leak checks to unit tests.
Goroutine Leak in Go means that some goroutines do not exit normally after startup, resulting in continuous resource utilization, which may eventually exhaust system resources or cause performance problems. Although Go's concurrent model is lightweight and efficient, once a leak occurs, it is not easy to troubleshoot.

To discover and solve goroutine leak, the key is to understand its common scenarios and make good use of relevant tools.

How to tell if there is a goroutine leak?
The most intuitive way is to get the number of currently active goroutines through runtime.NumGoroutine()
. If this number continues to grow and does not decline after the program runs for a period of time, there is a very likely leak.
An easy way is to print the current goroutine number at the critical node of the program:

fmt.Println("Current goroutines:", runtime.NumGoroutine())
In addition, you can also use the pprof tool to observe the status distribution of goroutines:
import _ "net/http/pprof" go func() { http.ListenAndServe(":6060", nil) }()
Visit /debug/pprof/goroutine?debug=1
to see all currently active goroutine stack information, which helps locate unexited coroutines.
Several common cases of goroutine leakage
1. Send data to the closed channel or receive data from the unwritten channel
This is one of the most common causes of goroutine leaks. for example:
ch := make(chan int) go func() { <-ch // If no one writes data to ch, this goroutine will keep blocking}()
In this case, goroutine will hang forever and cannot exit.
Suggested practices:
- Ensure that each receive operation has a corresponding sender;
- Use
select
default
to avoid deadlocks; - Or use context to control the life cycle.
2. Forgot to close the channel, causing the waiter to be unable to exit
For example, waiting for channel data in a loop, but the producer exits early and the channel is not closed, and the consumer will block for a long time.
for v := range ch { // If ch is not closed, I will wait here for fmt.Println(v) }
Suggested practices:
- After the production party completes the task, remember to close the channel;
- When the consumer handles, set the timeout mechanism in combination with
context
.
3. Forgot to cancel the context, causing the goroutine to fail to exit
Many network requests and database calls rely on context.Context to control the life cycle. If you forget cancel, the background task may be hang.
ctx, _ := context.WithCancel(context.Background()) go doSomething(ctx) // Forgot to call cancel()
Suggested practices:
- Use
defer cancel()
to ensure that the context can be released correctly; - For long-cycle tasks, consider setting deadline or timeout.
Use tools to assist detection
Use -test.coverprofile
or pprof
to detect leaks
Go's own testing tools can be used to detect potential leaks:
go test -bench=. -benchmem -cpu=4 -coverprofile=coverage.out
In addition, pprof provides detailed goroutine stack information, which can help you quickly find "stuck" coroutines.
Use gRPC or third-party libraries for integrated detection
Some projects have introduced test libraries like leaktest to check whether there are active goroutines after unit tests are finished.
defer require.LeakCheck(t)
This method is suitable as a quality assurance method in CI.
Summary of some practical skills
- All started goroutines must have clear exit conditions;
- Use context to control the life cycle more frequently;
- Before channel operation, make sure there is a sender/receiver;
- Use defer to close the resource or cancel the context;
- Regularly use pprof to check the goroutine distribution;
- Add leak check to unit tests;
Basically all this is it. Although goroutine leakage is hidden, it can still be effectively avoided as long as the structure is clear and the logic is controllable.
The above is the detailed content of golang goroutine leak detection. For more information, please follow other related articles on the PHP Chinese website!

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