GL.createCapabilities() can't find current context with GLFW OSMesa

[skoeven]

Environment

• LWJGL version: 3.2.3
• LWJGL build #: SNAPSHOT
• Java version: 1.8
• Platform: Linux (Ubuntu Server 20.04)
• Module: glfw

Description

I am attempting to use OSMesa with GLFW via the GLFW_OSMESA_CONTEXT_API window hint on a headless VM with no GPU. I can create a window successfully and get an OpenGL context but when I call GL.createCapabilities() it fails with the error: Exception in thread "main" java.lang.IllegalStateException: There is no OpenGL context current in the current thread.

At first I thought that maybe the OSMesa support wasn't working in the GLFW native library provided by LWJGL so I compiled GLFW with only OSMesa but got the same error.

Here is the code I am running to test this:

package test;

import org.lwjgl.glfw.GLFWErrorCallback;
import org.lwjgl.opengl.GL;

import static org.lwjgl.glfw.GLFW.GLFW_CLIENT_API;
import static org.lwjgl.glfw.GLFW.GLFW_CONTEXT_CREATION_API;
import static org.lwjgl.glfw.GLFW.GLFW_CONTEXT_VERSION_MAJOR;
import static org.lwjgl.glfw.GLFW.GLFW_CONTEXT_VERSION_MINOR;
import static org.lwjgl.glfw.GLFW.GLFW_FALSE;
import static org.lwjgl.glfw.GLFW.GLFW_OPENGL_API;
import static org.lwjgl.glfw.GLFW.GLFW_OSMESA_CONTEXT_API;
import static org.lwjgl.glfw.GLFW.GLFW_VISIBLE;
import static org.lwjgl.glfw.GLFW.glfwCreateWindow;
import static org.lwjgl.glfw.GLFW.glfwDestroyWindow;
import static org.lwjgl.glfw.GLFW.glfwGetCurrentContext;
import static org.lwjgl.glfw.GLFW.glfwGetVersionString;
import static org.lwjgl.glfw.GLFW.glfwGetWindowAttrib;
import static org.lwjgl.glfw.GLFW.glfwInit;
import static org.lwjgl.glfw.GLFW.glfwMakeContextCurrent;
import static org.lwjgl.glfw.GLFW.glfwSetErrorCallback;
import static org.lwjgl.glfw.GLFW.glfwTerminate;
import static org.lwjgl.glfw.GLFW.glfwWindowHint;
import static org.lwjgl.opengl.GL11.GL_RENDERER;
import static org.lwjgl.opengl.GL11.GL_VENDOR;
import static org.lwjgl.opengl.GL11.GL_VERSION;
import static org.lwjgl.opengl.GL11.glGetString;

public class TestMain {
    public static void main(String[] args) {
	System.out.println("Attempting to create window using GLFW " + glfwGetVersionString());

	glfwSetErrorCallback(GLFWErrorCallback.createPrint());

	if (!glfwInit()) {
		throw new RuntimeException("Failed to init GLFW");
	}

	glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_OSMESA_CONTEXT_API);
	glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);

	long window = glfwCreateWindow(640, 480, "Test", 0, 0);

	if(window == 0) {
		glfwTerminate();
		throw new RuntimeException("Failed to create window!");
	} else {
		glfwMakeContextCurrent(window);
		long context = glfwGetCurrentContext();
		if (context == window) {
			System.out.println("glfwGetCurrentContext() - Found window context.");
		}

		if (GLFW_OSMESA_CONTEXT_API == glfwGetWindowAttrib(window, GLFW_CONTEXT_CREATION_API)) {
			System.out.println("Using OSMesa context creation api");
		}

		int client = glfwGetWindowAttrib(window, GLFW_CLIENT_API);
		int major = glfwGetWindowAttrib(window, GLFW_CONTEXT_VERSION_MAJOR);
		int minor = glfwGetWindowAttrib(window, GLFW_CONTEXT_VERSION_MINOR);
		if (client == GLFW_OPENGL_API) {
			System.out.println("Context = OpenGL " + major + "." + minor);
		}

		GL.createCapabilities();
	}

	System.out.println("OpenGL Vendor: " + glGetString(GL_VENDOR));
	System.out.println("OpenGL Renderer: " + glGetString(GL_RENDERER));
	System.out.println("OpenGL Version: " + glGetString(GL_VERSION));

	glfwDestroyWindow(window);
	glfwTerminate();
    }
}

Here is the command used to run the code while using the LWJGL provided libglfw.so:
Command:
xvfb-run -a -s "-screen 0 1024x768x16" java -Dorg.lwjgl.util.Debug=true -jar OSMesaTest-1.0-SNAPSHOT-all.jar

Output:
[LWJGL] Version: 3.2.3 SNAPSHOT
[LWJGL] OS: Linux v5.4.0-48-generic
[LWJGL] JRE: 1.8.0_265 amd64
[LWJGL] JVM: OpenJDK 64-Bit Server VM v25.265-b01 by Private Build
[LWJGL] Loading JNI library: lwjgl
[LWJGL] Module: org.lwjgl
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/liblwjgl.so
[LWJGL] Loading library: glfw
[LWJGL] Module: org.lwjgl.glfw
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/libglfw.so
Attempting to create window using GLFW 3.4.0 X11 GLX EGL OSMesa clock_gettime evdev shared
[LWJGL] Warning: Failed to instantiate memory allocator: org.lwjgl.system.jemalloc.JEmallocAllocator. Using the system default.
[LWJGL] MemoryUtil allocator: StdlibAllocator
glfwGetCurrentContext() - Found window context.
Using OSMesa context creation api
Context = OpenGL 3.1
[LWJGL] Loading JNI library: lwjgl_opengl
[LWJGL] Module: org.lwjgl.opengl
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/liblwjgl_opengl.so
[LWJGL] Loading library: libGL.so.1
[LWJGL] Module: org.lwjgl.opengl
[LWJGL] libGL.so.1 not found in org.lwjgl.librarypath=/tmp/lwjglender/3.2.3-SNAPSHOT
[LWJGL] Loaded from system paths: /lib/x86_64-linux-gnu/libGL.so.1
Exception in thread "main" java.lang.IllegalStateException: There is no OpenGL context current in the current thread.
at org.lwjgl.opengl.GL.createCapabilities(GL.java:378)
at org.lwjgl.opengl.GL.createCapabilities(GL.java:322)
at TestMain.checkOpenGLCompatability(TestMain.java:68)
at TestMain.main(TestMain.java:27)

Here is the command I ran while using GLFW compiled with only OSMesa support (no need for xvfb with OSMesa only):
Command:
java -Dorg.lwjgl.util.Debug=true -jar OSMesaTest-1.0-SNAPSHOT-all.jar

Output:
[LWJGL] Version: 3.2.3 SNAPSHOT
[LWJGL] OS: Linux v5.4.0-48-generic
[LWJGL] JRE: 1.8.0_265 amd64
[LWJGL] JVM: OpenJDK 64-Bit Server VM v25.265-b01 by Private Build
[LWJGL] Loading JNI library: lwjgl
[LWJGL] Module: org.lwjgl
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/liblwjgl.so
[LWJGL] Loading library: glfw
[LWJGL] Module: org.lwjgl.glfw
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/libglfw.so
Attempting to create window using GLFW 3.4.0 null OSMesa
[LWJGL] Warning: Failed to instantiate memory allocator: org.lwjgl.system.jemalloc.JEmallocAllocator. Using the system default.
[LWJGL] MemoryUtil allocator: StdlibAllocator
glfwGetCurrentContext() - Found window context.
Using OSMesa context creation api
Context = OpenGL 3.1
[LWJGL] Loading JNI library: lwjgl_opengl
[LWJGL] Module: org.lwjgl.opengl
[LWJGL] Loaded from org.lwjgl.librarypath: /tmp/lwjglender/3.2.3-SNAPSHOT/liblwjgl_opengl.so
[LWJGL] Loading library: libGL.so.1
[LWJGL] Module: org.lwjgl.opengl
[LWJGL] libGL.so.1 not found in org.lwjgl.librarypath=/tmp/lwjglender/3.2.3-SNAPSHOT
[LWJGL] Loaded from system paths: /lib/x86_64-linux-gnu/libGL.so.1
Exception in thread "main" java.lang.IllegalStateException: There is no OpenGL context current in the current thread.
at org.lwjgl.opengl.GL.createCapabilities(GL.java:378)
at org.lwjgl.opengl.GL.createCapabilities(GL.java:322)
at TestMain.checkOpenGLCompatability(TestMain.java:68)
at TestMain.main(TestMain.java:27)

The output is identical aside from the GLFW version used. Any idea why this is happening? Is this a bug in LWJGL or am I doing something stupid?

[Spasi]

LWJGL must use OSMesaGetProcAddress to retrieve OpenGL function pointers. Will be fixed in the next snapshot. Bindings for GLFW's OSMesa functions will also be added.

[skoeven]

Awesome, thank you!