Memory leak in hello world

Thejaswi Puthraya thejaswi.puthraya at gmail.com
Mon Jan 27 01:44:48 PST 2014


I have a simple "Hello World" program (file named "tmp.d") 
written in D

import std.stdio;

void main() {
   printf("Hello World\n");
}

I successfully compiled the above program with the DMD64 D 
compiler v2.064 on linux x86_64 (libc 2.18 just in case 
required). But valgrind reports memory leaks while running the 
program.

valgrind --leak-check=full ./tmp
==11356== Memcheck, a memory error detector
==11356== Copyright (C) 2002-2013, and GNU GPL'd, by Julian 
Seward et al.
==11356== Using Valgrind-3.9.0 and LibVEX; rerun with -h for 
copyright info
==11356== Command: ./tmp
==11356==
Hello World
==11356==
==11356== HEAP SUMMARY:
==11356==     in use at exit: 88 bytes in 2 blocks
==11356==   total heap usage: 25 allocs, 23 frees, 53,016 bytes 
allocated
==11356==
==11356== 16 bytes in 1 blocks are definitely lost in loss record 
1 of 2
==11356==    at 0x4A0645D: malloc (in 
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==11356==    by 0x43E366: thread_attachThis (in /home/theju/tmp)
==11356==    by 0x43E1F6: thread_init (in /home/theju/tmp)
==11356==    by 0x4361D8: gc_init (in /home/theju/tmp)
==11356==    by 0x42E627: rt_init (in /home/theju/tmp)
==11356==    by 0x426CD5: 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZi6runAllMFZv (in 
/home/theju/tmp)
==11356==    by 0x426C91: 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZi7tryExecMFMDFZvZv (in 
/home/theju/tmp)
==11356==    by 0x426C12: _d_run_main (in /home/theju/tmp)
==11356==    by 0x426606: main (in /home/theju/tmp)
==11356==
==11356== 72 bytes in 1 blocks are definitely lost in loss record 
2 of 2
==11356==    at 0x4A081D4: calloc (in 
/usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==11356==    by 0x444A95: _d_monitor_create (in /home/theju/tmp)
==11356==    by 0x43A181: _d_monitorenter (in /home/theju/tmp)
==11356==    by 0x43DF19: _D4core6thread6Thread8isDaemonMFNdZb 
(in /home/theju/tmp)
==11356==    by 0x435AAB: 
_D4core6thread14thread_joinAllUZv14__foreachbody1MFKC4core6thread6ThreadZi 
(in /home/theju/tmp)
==11356==    by 0x43DFB8: 
_D4core6thread6Thread7opApplyFMDFKC4core6thread6ThreadZiZi (in 
/home/theju/tmp)
==11356==    by 0x435A24: thread_joinAll (in /home/theju/tmp)
==11356==    by 0x42E6BC: rt_term (in /home/theju/tmp)
==11356==    by 0x426D05: 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZi6runAllMFZv (in 
/home/theju/tmp)
==11356==    by 0x426C91: 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZi7tryExecMFMDFZvZv (in 
/home/theju/tmp)
==11356==    by 0x426C12: _d_run_main (in /home/theju/tmp)
==11356==    by 0x426606: main (in /home/theju/tmp)
==11356==
==11356== LEAK SUMMARY:
==11356==    definitely lost: 88 bytes in 2 blocks
==11356==    indirectly lost: 0 bytes in 0 blocks
==11356==      possibly lost: 0 bytes in 0 blocks
==11356==    still reachable: 0 bytes in 0 blocks
==11356==         suppressed: 0 bytes in 0 blocks
==11356==
==11356== For counts of detected and suppressed errors, rerun 
with: -v
==11356== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 2 
from 2)

One IRC user on #d seemed to suggest that this is a long term GC 
issue. Is this right? A little more explanation about what is 
happening will be very helpful.


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