[libdispatch-dev] Memory issues with libdispatch

[Aldrin Martoq Ahumada]

I will learn how to use the heap tool and tell you later, thanks. The weird thing is any tool I use, none reports memory leaks.

But as I told you: my process goes back to 2 threads and memory usage NEVER goes down in Activity Monitor after that (check pic #3).


Thanks!

Aldrin Martoq A.
http://aldrin.martoq.cl/

On Apr 30, 2012, at 3:47 PM, Daniel A. Steffen wrote:

> please use the 'heap' tool on Mac OS X, that gives you the actual sizes of the heap memory allocated by the program and not the very indirect measure of the page usage as seen by the kernel.
> 
> also make sure you wait until the process is back to two threads before measuring, to ensure that the continuation cache for the worker thread has indeed been freed.
> 
> On Apr 30, 2012, at 12:39, Aldrin Martoq Ahumada <aldrin.martoq at gmail.com> wrote:
> 
>> Hi Daniel,
>> 
>> I'm using Activity Monitor (OS X) and top (linux).
>> 
>> 1) Here we have 1.9MiB initially (no SIGHUP sent yet)
>> http://cl.ly/2P1o3s3T0P1X0l1D390W
>> 
>> 2) Here we have 147MiB while the loop is running (SIGHUP sent)
>> http://cl.ly/473x2U1v2W1h1141441k
>> 
>> 3) Here we have 24.7MiB after everything is done
>> http://cl.ly/0n0S3K3t3n2C0t1y393l
>> 
>> 4) If I send the signal again, memory increases everytime (26.0 MiB here)
>> http://cl.ly/0B2E2g3V021f0s2w3T2v
>> 
>> 
>> Memory never goes down after that, in Linux it is worst.
>> 
>> 
>> 
>> Thanks for the note on dispatch_async(), It was not there originally… I was trying to make it work and adding autoreleasepools just in case, but nothing seemed to work ;)
>> 
>> 
>> 
>> Regards,
>> 
>> Aldrin Martoq A.
>> http://aldrin.martoq.cl/
>> 
>> On Apr 30, 2012, at 3:07 PM, Daniel A. Steffen wrote:
>> 
>>> Aldrin,
>>> 
>>> how are you measuring this memory usage growth? I cannot reproduce it on Mac OS X with the 'heap' tool
>>> 
>>> You might be seeing the temporary effects of the libdispatch continuation cache, these are small buffers that get allocated for each dispatch_async() and cached on a per-thread basis for speed. That cache is freed once a temporary dispatch worker thread exits ( a couple of seconds after SIGHUP in your example, on Mac OS X at least)
>>> 
>>> Also note that there is no need to dispatch_async() from your source event handler since you are already on the main queue at that point (the target queue of the source)
>>> 
>>> Daniel
>>> 
>>> On Apr 29, 2012, at 23:09, Aldrin Martoq Ahumada <aldrin.martoq at gmail.com> wrote:
>>> 
>>>> 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/
>>>> 
>>>> _______________________________________________
>>>> libdispatch-dev mailing list
>>>> libdispatch-dev at lists.macosforge.org
>>>> http://lists.macosforge.org/mailman/listinfo.cgi/libdispatch-dev
>>> 
>> 
> 

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