spidermonkey 1.8.5 crashes in debug mode

Question

I am using Spidermonkey 1.8.5 in my application. My application crashes when I use the debug JS library. I am building the library with the following options: --enable-debug --disable-optimize --enable-threadsafe

crash is pointing here: Assertion failure: (cx)->thread->data.requestDepth || (cx)->thread == (cx)->runtime->gcThread, at ../../src/jsapi.cpp

Here is the sample program

/* Include the JSAPI header file to get access to SpiderMonkey. */
#include "jsapi.h"



/* The class of the global object. */
static JSClass global_class = {
    "global", JSCLASS_GLOBAL_FLAGS,
    JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_StrictPropertyStub,
    JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub,
    JSCLASS_NO_OPTIONAL_MEMBERS
};

/* The error reporter callback. */
void reportError(JSContext *cx, const char *message, JSErrorReport *report)
{
    fprintf(stderr, "%s:%u:%s\n",
            report->filename ? report->filename : "<no filename=\"filename\">",
            (unsigned int) report->lineno,
            message);
}

int main(int argc, const char *argv[])
{
    /* JSAPI variables. */
    JSRuntime *rt;
    JSContext *cx;
    JSObject  *global;
    printf("Started\n");
    /* Create a JS runtime. You always need at least one runtime per process. */
    rt = JS_NewRuntime(8 * 1024 * 1024);

    if (rt == NULL)
        return 1;

    /*
     * Create a context. You always need a context per thread.
     * Note that this program is not multi-threaded.
     */
    cx = JS_NewContext(rt, 8192);
    if (cx == NULL)
        return 1;

    JS_SetErrorReporter(cx, reportError);

    /*
     * Create the global object in a new compartment.
     * You always need a global object per context.
     */
    global = JS_NewCompartmentAndGlobalObject(cx, &global_class, NULL);
    if (global == NULL)
        return 1;

    /*
     * Populate the global object with the standard JavaScript
     * function and object classes, such as Object, Array, Date.
     */
    if (!JS_InitStandardClasses(cx, global))
        return 1;

    /* Your application code here. This may include JSAPI calls
     * to create your own custom JavaScript objects and to run scripts.
     *
     * The following example code creates a literal JavaScript script,
     * evaluates it, and prints the result to stdout.
     *
     * Errors are conventionally saved in a JSBool variable named ok.
     */
    char *script = "'Hello ' + 'World!'";
    jsval rval;
    JSString *str;
    JSBool ok;
    const char *filename = "noname";
    uintN lineno = 0;

    ok = JS_EvaluateScript(cx, global, script, strlen(script),
                           filename, lineno, &rval);
    if (rval == NULL | rval == JS_FALSE)
        return 1;

    str = JS_ValueToString(cx, rval);
    printf("%s\n", JS_EncodeString(cx, str));

    /* End of your application code */

    /* Clean things up and shut down SpiderMonkey. */
    JS_DestroyContext(cx);
    JS_DestroyRuntime(rt);
    JS_ShutDown();
    return 0;
}

If I am building in release mode the program works fine. this problem is only with the debug mode. What am I missing here?

Answer 1

Insert JS_BeginRequest(cx); just before the JS_NewCompartmentAndGlobalObject call.

Insert JS_EndRequest(cx); just before the call to JS_DestroyContext.

Most JSAPI functions require a request. (I'm not sure why. The original reason for threads had to do with multithreading, but each JSRuntime is single-threaded now.)

The debug build of SpiderMonkey includes assertions that check API usage in ways that release mode can't. So you will likely see debug-only assertions again. I strongly recommend developing against a debug build, because those assertions almost always indicate real problems.

The next SpiderMonkey release is coming soon: https://bugzilla.mozilla.org/show_bug.cgi?id=735599#c54