glimagesink error `!xcb_xlib_threads_sequence_lost' failed.

For each video item in a list, the app:
1) creates a new pipeline "playbin video-sink=glimagesink"
2) at end of video item cleans pipeline

The main() function calls XInitThread() right at its beginning.
The app renders in its own GLX window using libglfw (receiving samples/textures from glimagesink's client-draw callback). The application context is shared with each pipeline through bus sync-message (GST_MESSAGE_NEED_CONTEXT)

Often the app aborts with X11 assertion:

[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
info-beamer: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.

The error can happen from :
- gst_gl_context_create_thread / gst_gl_context_glx_create_context / glXCreateContextAttribsARB
- libglfw.so.3 / XPending

Application's X11 display/context is used to create a GstGLcontext/GstGLDisplay for every item/pipeline. (Or should this be done only once in the beginning of main?)


    x11_display = glXGetCurrentDisplay();
    x11_window = (Window) glXGetCurrentDrawable();

    glx_context = glXGetCurrentContext ();
    platform = "glx";

    gl_display =
            (GstGLDisplay *) gst_gl_display_x11_new_with_display (x11_display);
    gl_context =
            gst_gl_context_new_wrapped (gl_display, (guintptr) glx_context,
                    gst_gl_platform_from_string (platform),
        GST_GL_API_OPENGL);

gl_display, gl_context are used in sync-message bus callback to share display and context with pipeline.