The context for this bug is using the command buffer shared library in Skia tests. Skia loads the library and then interacts with it using its exported EGL and GL interface.

Currently every call to eglGetDisplay() returns a new egl::Display object. When eglInitialize() is called Display::Initialize() is called on the display which in turn calls gles2::Initialize(). This last function sets up the TLS key that is used to store the current GL context, called g_gl_context_key.

Likewise, when eglTerminate is called on a display egl::Display::~Display() is called which calls gles2::Terminate(). gles2::Terminate frees g_gl_context_key.

The Skia test suite sometimes creates multiple GL contexts. The Skia GL context wrapper class calls eglGetDisplay(GL_DEFAULT_DISPLAY) and eglInitiailize() when a context is created and eglTerminate() when the context is destroyed. Each context gets its own display since eglGetDisplay always returns a new object.

A problem arises if we create two contexts, A and B. If A is destroyed it becomes impossible to safely use B because the TLS key for the current context no longer exists.

I can probably work around this, but am filing the bug to document my findings.