Hi, I have been testing sample code from the wiki and found that libdispatch is alloc'ing a lot of memory without releasing it, both in OS X (Lion 10.7.3, Xcode 4.3.2) and Linux (manually compiled and installed). The code creates a SIGHUP signal source, with a handler that calls 100_000 writes to a logfile. The write to a log is queued in a serial queue. The first run shows normal memory usage (8-9 MiB both Linux and OS X). After sending a "kill -1 <pid>" memory usage increases 1-20MiB every time I send the SIGHUP signal. I have tried compiling with -fobj-arc and without it, but the result is the same. I removed the NSString usage in the br_log function, but the leak is not there: it is somewhere inside libdispatch. I tried both valgrind and Xcode Instruments, but no leaks are found. Thanks in advance, ---- ini ---- // // main.m // test02 // // Created by Aldrin Martoq on 4/29/12. // Copyright (c) 2012 __MyCompanyName__. All rights reserved. // #include <unistd.h> #import <Foundation/Foundation.h> #import <dispatch/dispatch.h> static FILE *log_file = NULL; static NSString *log_filename = @"/tmp/br.log"; static dispatch_queue_t log_queue; void br_log(NSString *format, ...) { @autoreleasepool { va_list ap; va_start(ap, format); NSString *s = [[NSString alloc] initWithFormat:format arguments:ap]; va_end(ap); if (log_file == NULL) { log_queue = dispatch_queue_create("cl.martoq.log_queue", NULL); log_file = fopen([log_filename cStringUsingEncoding:NSUTF8StringEncoding], "a"); NSLog(@"Log file created: %@", log_filename); } dispatch_async(log_queue, ^{ @autoreleasepool { const char *c = [s cStringUsingEncoding:NSUTF8StringEncoding]; fputs(c, log_file); fputs("\n", log_file); fflush(log_file); [s release]; } }); } } void br_setup() { signal(SIGHUP, SIG_IGN); dispatch_source_t sig_src = dispatch_source_create(DISPATCH_SOURCE_TYPE_SIGNAL, SIGHUP, 0, dispatch_get_main_queue()); dispatch_source_set_event_handler(sig_src, ^{ dispatch_async(dispatch_get_main_queue(), ^{ printf("Caught SIGHUP\n"); for (int i = 0; i < 100000; i++) { br_log(@"prueba: %d", i); } }); }); dispatch_resume(sig_src); } int main(int argc, const char * argv[]) { @autoreleasepool { // insert code here... NSLog(@"Hello, World!"); br_setup(); dispatch_main(); } return 0; } ---- fini ---- Aldrin Martoq A. http://aldrin.martoq.cl/