## How to Debug a Go C-Shared Library Hanging on HTTPS.Post() After Forking?

Debugging a Hanging Go C-Shared Library on HTTPS.Post()

In the described issue, a C-shared library written in Go experiences a hang while attempting HTTPS.Post(). While the executable binary runs correctly, the shared library encounters this problem upon using http.Post() or net.Dial().

Initial Investigations:

• strace: Revealed a hang on futex() calls.
• Profiler: Showed that the profiler itself became unresponsive.

Stack Trace:

The SIGQUIT stack trace indicated that the thread was hung on runtime.futexsleep(), which is used for thread synchronization.

Possible Cause and Solution:

As mentioned in the resolved answer, the root cause lies in the way the Go shared library is loaded. When the shared library is linked to a C or C application, the Go runtime is initialized during the application startup. This can lead to unpredictable behavior if the application forks processes and tries to use the Go library in the forked processes.

Solution:

To address this issue, it is necessary to load the Go shared library after the fork has occurred. This can be achieved by using dynamic linking techniques such as dlopen() and dlsym(). This approach ensures that the Go runtime is only initialized when it is needed within the forked process.

Conclusion:

The problem with the hanging C-shared library was due to the premature initialization of the Go runtime. By loading the library dynamically after forking, the issue was resolved, and the shared library functioned correctly.

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