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Bug 4278

Summary: On macOS Mojave: Program hangs when using SDL Renderer one one thread and OpenGL on another
Product: SDL Reporter: Daniel Bokser <dan.bokser>
Component: videoAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: major    
Priority: P2 CC: dan.bokser, icculus, sezeroz
Version: 2.0.8   
Hardware: x86_64   
OS: Mac OS X (All)   
Attachments: Simple program with SDL Renderer on main thread and OpenGL on another

Description Daniel Bokser 2018-09-28 00:00:59 UTC 
Created attachment 3320 [details]
Simple program with SDL Renderer on main thread and OpenGL on another

On Mojave and Xcode 10, my program hangs after a few seconds when rendering using an SDL Renderer on the main thread and using OpenGL on another. I have attached a simple program that demonstrates this.  Looks like both thread are stuck on [nsContext flushBuffer] in Cocoa_GL_SwapWindow() in SDL_cocoaopengl.m. This is with Ryan's fix on https://bugzilla.libsdl.org/show_bug.cgi?id=4272

This program works fine when compiling with Xcode 9.
Comment 1 Ryan C. Gordon 2018-10-19 03:39:10 UTC 
Mojave appears to have a deadlock if you swap two separate windows/contexts from two separate threads at the same time; I stuck a mutex around our swap code which appears to fix it.

That fix is https://hg.libsdl.org/SDL/rev/84eaa0636bac

--ryan.
Comment 2 Daniel Bokser 2018-10-23 03:48:59 UTC 
Thank you! This fixed the deadlock issue for me.  However, my SDL project is still not completely fixed in Mojave.  I have opened up another issue here: https://bugzilla.libsdl.org/show_bug.cgi?id=4329