How to Get Stack Traces for All Goroutines in a Running Go Process?

How to Dump Stack Traces for All Goroutines in a Running Go Process

When debugging or troubleshooting a Go process, obtaining stack traces for all its goroutines can be crucial. However, doing so without modifying the source code or terminating the process can be challenging. This guide provides a solution to this problem.

The Go runtime includes a feature that allows you to dump stack traces on demand. However, invoking this feature from outside the process is not immediately apparent.

Using a Signal Handler

To capture stack traces for all goroutines, you can set up a signal handler that listens for a specific signal. When the signal is received, the handler will generate and print the stack traces.

Here's an example code snippet:

<code class="go">import (
    "fmt"
    "os"
    "os/signal"
    "runtime"
    "syscall"
)

func main() {
    // Create a channel to receive signals.
    sigChan := make(chan os.Signal)

    // Start a goroutine that will write stack traces to the channel.
    go func() {
        // Create a buffer to hold the stack trace.
        stacktrace := make([]byte, 8192)

        // Loop until a signal is received.
        for _ = range sigChan {
            length := runtime.Stack(stacktrace, true)
            fmt.Println(string(stacktrace[:length]))
        }
    }()

    // Register to receive SIGQUIT signals.
    signal.Notify(sigChan, syscall.SIGQUIT)

    // Continue with the main application logic.
    ...
}</code>

Sending the Signal

Once the handler is set up, you can send the SIGQUIT signal to the process to trigger the stack trace dump. You can do this using the following command:

kill -QUIT <process id></process>

Where is the ID of the Go process.

Example Usage

Here's an example scenario:

1. Run the code snippet provided above as a separate Go process.

2. When the process is running, open a terminal window and enter the kill command:

   kill -QUIT <process id></process>

The stack traces for all the goroutines in the Go process will be printed in the terminal window.

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