3. A good old segfault: Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 1026 (LWP 712)] 0x404dd042 in _swrast_InvalidateState () from /usr/X11R6/lib/modules/dri/radeon_dri.so (gdb) bt #0 0x404dd042 in _swrast_InvalidateState () from /usr/X11R6/lib/modules/dri/radeon_dri.so #1 0x4058b6ac in radeonInvalidateState () from /usr/X11R6/lib/modules/dri/radeon_dri.so #2 0x404a6edd in _mesa_update_state () from /usr/X11R6/lib/modules/dri/radeon_dri.so #3 0x4045e0e0 in _mesa_Clear () from /usr/X11R6/lib/modules/dri/radeon_dri.so #4 0x401132f5 in _ts_Clear () from /usr/X11R6/lib/libGL.so.1 #5 0x08049275 in draw_loop () #6 0x0804995a in thread_function () #7 0x40337fa5 in pthread_start_thread () from /lib/libpthread.so.0 #8 0x40337fed in pthread_start_thread_event () from /lib/libpthread.so.0
This occurs because you have modified the X event loop to destroy a context that *IS STILL IN USE* in another thread. GL doesn't provide any guarantees about what will happen if you try to do this...
One way to achieve something like what you want would be to make ExitFlag an array, and destroy the context at the end of draw_loop. I've attached something that does this.
This doesn't solve all of your problems, though - I'm still looking at them.
Keith
/* $Id: glthreads.c,v 1.1 2000/07/20 20:12:17 brianp Exp $ */
/* modified by [EMAIL PROTECTED] to destroy current window and context when
* key pressed...
*/
/*
* Copyright (C) 2000 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* This program tests GLX thread safety.
* Command line options:
* -n <num threads> Number of threads to create (default is 2)
* -display <display name> Specify X display (default is :0.0)
*
* Brian Paul 20 July 2000
*/
#if defined(PTHREADS) /* defined by Mesa on Linux and other platforms */
#include <GL/gl.h>
#include <GL/glx.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
/*
* Each window/thread/context:
*/
struct winthread {
Display *Dpy;
int Index;
pthread_t Thread;
Window Win;
GLXContext Context;
float Angle;
int WinWidth, WinHeight;
GLboolean NewSize;
GLboolean ExitFlag;
};
#define MAX_WINTHREADS 100
static struct winthread WinThreads[MAX_WINTHREADS];
static int NumWinThreads = 0;
static void
Error(const char *msg)
{
fprintf(stderr, "Error: %s\n", msg);
exit(1);
}
/* draw a colored cube */
static void
draw_object(void)
{
glPushMatrix();
glScalef(0.75, 0.75, 0.75);
glColor3f(1, 0, 0);
glBegin(GL_POLYGON);
glVertex3f(1, -1, -1);
glVertex3f(1, 1, -1);
glVertex3f(1, 1, 1);
glVertex3f(1, -1, 1);
glEnd();
glColor3f(0, 1, 1);
glBegin(GL_POLYGON);
glVertex3f(-1, -1, -1);
glVertex3f(-1, 1, -1);
glVertex3f(-1, 1, 1);
glVertex3f(-1, -1, 1);
glEnd();
glColor3f(0, 1, 0);
glBegin(GL_POLYGON);
glVertex3f(-1, 1, -1);
glVertex3f( 1, 1, -1);
glVertex3f( 1, 1, 1);
glVertex3f(-1, 1, 1);
glEnd();
glColor3f(1, 0, 1);
glBegin(GL_POLYGON);
glVertex3f(-1, -1, -1);
glVertex3f( 1, -1, -1);
glVertex3f( 1, -1, 1);
glVertex3f(-1, -1, 1);
glEnd();
glColor3f(0, 0, 1);
glBegin(GL_POLYGON);
glVertex3f(-1, -1, 1);
glVertex3f( 1, -1, 1);
glVertex3f( 1, 1, 1);
glVertex3f(-1, 1, 1);
glEnd();
glColor3f(1, 1, 0);
glBegin(GL_POLYGON);
glVertex3f(-1, -1, -1);
glVertex3f( 1, -1, -1);
glVertex3f( 1, 1, -1);
glVertex3f(-1, 1, -1);
glEnd();
glPopMatrix();
}
/* signal resize of given window */
static void
resize(struct winthread *wt, int w, int h)
{
wt->NewSize = GL_TRUE;
wt->WinWidth = w;
wt->WinHeight = h;
}
/*
* We have an instance of this for each thread.
*/
static void
draw_loop(struct winthread *wt)
{
while (!wt->ExitFlag) {
glXMakeCurrent(wt->Dpy, wt->Win, wt->Context);
glEnable(GL_DEPTH_TEST);
if (wt->NewSize) {
GLfloat w = (float) wt->WinWidth / (float) wt->WinHeight;
glViewport(0, 0, wt->WinWidth, wt->WinHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-w, w, -1.0, 1.0, 1.5, 10);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0, 0, -2.5);
wt->NewSize = GL_FALSE;
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glRotatef(wt->Angle, 0, 0, 1);
glRotatef(wt->Angle, 1, 0, 0);
glScalef(0.7, 0.7, 0.7);
draw_object();
glPopMatrix();
glXSwapBuffers(wt->Dpy, wt->Win);
wt->Angle += 1.0;
}
glXDestroyContext(wt->Dpy, wt->Context);
XDestroyWindow(wt->Dpy, wt->Win);
}
/*
* The main process thread runs this loop.
*/
static void
event_loop(Display *dpy)
{
int count;
do {
static long mask = StructureNotifyMask | ExposureMask | KeyPressMask;
XEvent event;
int i;
for (count = 0, i = 0; i < NumWinThreads; i++) {
struct winthread *wt = &WinThreads[i];
if (!wt->ExitFlag)
count++;
else
continue;
while (XCheckWindowEvent(dpy, wt->Win, mask, &event)) {
if (event.xany.window == wt->Win) {
switch (event.type) {
case ConfigureNotify:
resize(wt, event.xconfigure.width,
event.xconfigure.height);
break;
case KeyPress:
wt->ExitFlag = 1;
break;
default:
/*no-op*/ ;
}
}
else {
printf("window mismatch\n");
}
}
}
} while (count);
}
/*
* we'll call this once for each thread, before the threads are created.
*/
static void
create_window(struct winthread *wt)
{
Window win;
GLXContext ctx;
int attrib[] = { GLX_RGBA,
GLX_RED_SIZE, 1,
GLX_GREEN_SIZE, 1,
GLX_BLUE_SIZE, 1,
GLX_DEPTH_SIZE, 1,
GLX_DOUBLEBUFFER,
None };
int scrnum;
XSetWindowAttributes attr;
unsigned long mask;
Window root;
XVisualInfo *visinfo;
int width = 80, height = 80;
int xpos = (wt->Index % 10) * 90;
int ypos = (wt->Index / 10) * 100;
scrnum = DefaultScreen(wt->Dpy);
root = RootWindow(wt->Dpy, scrnum);
visinfo = glXChooseVisual(wt->Dpy, scrnum, attrib);
if (!visinfo) {
Error("Unable to find RGB, Z, double-buffered visual");
}
/* window attributes */
attr.background_pixel = 0;
attr.border_pixel = 0;
attr.colormap = XCreateColormap(wt->Dpy, root, visinfo->visual, AllocNone);
attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
win = XCreateWindow(wt->Dpy, root, xpos, ypos, width, height,
0, visinfo->depth, InputOutput,
visinfo->visual, mask, &attr);
if (!win) {
Error("Couldn't create window");
}
{
XSizeHints sizehints;
sizehints.x = xpos;
sizehints.y = ypos;
sizehints.width = width;
sizehints.height = height;
sizehints.flags = USSize | USPosition;
XSetNormalHints(wt->Dpy, win, &sizehints);
XSetStandardProperties(wt->Dpy, win, "glthreads", "glthreads",
None, (char **)NULL, 0, &sizehints);
}
ctx = glXCreateContext(wt->Dpy, visinfo, NULL, True);
if (!ctx) {
Error("Couldn't create GLX context");
}
XMapWindow(wt->Dpy, win);
XSync(wt->Dpy, 0);
/* save the info for this window/context */
wt->Win = win;
wt->Context = ctx;
wt->Angle = 0.0;
wt->WinWidth = width;
wt->WinHeight = height;
wt->NewSize = GL_TRUE;
}
/*
* Called by pthread_create()
*/
static void *
thread_function(void *p)
{
struct winthread *wt = (struct winthread *) p;
draw_loop(wt);
return NULL;
}
/*
* called before exit to wait for all threads to finish
*/
static void
clean_up(void)
{
int i;
/* wait for threads to finish */
for (i = 0; i < NumWinThreads; i++) {
pthread_join(WinThreads[i].Thread, NULL);
}
for (i = 0; i < NumWinThreads; i++) {
glXDestroyContext(WinThreads[i].Dpy, WinThreads[i].Context);
XDestroyWindow(WinThreads[i].Dpy, WinThreads[i].Win);
}
}
int
main(int argc, char *argv[])
{
char *displayName = ":0.0";
int numThreads = 2;
Display *dpy;
int i;
Status threadStat;
if (argc == 1) {
printf("threadgl: test of GL thread safety (any key = exit)\n");
printf("Usage:\n");
printf(" threadgl [-display dpyName] [-n numthreads]\n");
}
else {
int i;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-display") == 0 && i + 1 < argc) {
displayName = argv[i + 1];
i++;
}
else if (strcmp(argv[i], "-n") == 0 && i + 1 < argc) {
numThreads = atoi(argv[i + 1]);
if (numThreads < 1)
numThreads = 1;
else if (numThreads > MAX_WINTHREADS)
numThreads = MAX_WINTHREADS;
i++;
}
}
}
/*
* VERY IMPORTANT: call XInitThreads() before any other Xlib functions.
*/
threadStat = XInitThreads();
if (threadStat) {
printf("XInitThreads() returned %d (success)\n", (int) threadStat);
}
else {
printf("XInitThreads() returned 0 (failure- this program may fail)\n");
}
dpy = XOpenDisplay(displayName);
if (!dpy) {
fprintf(stderr, "Unable to open display %s\n", displayName);
return -1;
}
NumWinThreads = numThreads;
/* Create the GLX windows and contexts */
for (i = 0; i < numThreads; i++) {
WinThreads[i].Dpy = dpy;
WinThreads[i].Index = i;
create_window(&WinThreads[i]);
}
/* Create the threads */
for (i = 0; i < numThreads; i++) {
pthread_create(&WinThreads[i].Thread, NULL, thread_function,
(void*) &WinThreads[i]);
printf("Created Thread %p\n", WinThreads[i].Thread);
}
event_loop(dpy);
clean_up();
XCloseDisplay(dpy);
return 0;
}
#else /* PTHREADS */
#include <stdio.h>
int
main(int argc, char *argv[])
{
printf("Sorry, this program wasn't compiled with PTHREADS defined.\n");
return 0;
}
#endif /* PTHREADS */
