Memory leak when unloading SF3

[derselbst]

FluidSynth version

2.0.4 and trunk

Current behavior

explicit unloading of a sf3 does not release memory

Other information

valgrind says:

==9970== 37,536 bytes in 2,346 blocks are still reachable in loss record 189 of 192
==9970==    at 0x4C2E01F: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==9970==    by 0x4E532E8: new_fluid_list (fluid_list.c:37)
==9970==    by 0x4E533CD: fluid_list_prepend (fluid_list.c:91)
==9970==    by 0x4E5FE4E: fluid_samplecache_load (fluid_samplecache.c:100)
==9970==    by 0x4E57DD5: fluid_defsfont_load_sampledata (fluid_defsfont.c:312)
==9970==    by 0x4E57F84: fluid_defsfont_load_all_sampledata (fluid_defsfont.c:379)
==9970==    by 0x4E58236: fluid_defsfont_load (fluid_defsfont.c:478)
==9970==    by 0x4E57890: fluid_defsfloader_load (fluid_defsfont.c:105)
==9970==    by 0x4E74EF4: fluid_synth_sfload (fluid_synth.c:4503)
==9970==    by 0x403328: main (fluidsynth.c:771)
==9970== 
==9970== 79,343 bytes in 2,346 blocks are still reachable in loss record 190 of 192
==9970==    at 0x4C2E01F: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==9970==    by 0x4E60139: new_samplecache_entry (fluid_samplecache.c:205)
==9970==    by 0x4E5FE21: fluid_samplecache_load (fluid_samplecache.c:92)
==9970==    by 0x4E57DD5: fluid_defsfont_load_sampledata (fluid_defsfont.c:312)
==9970==    by 0x4E57F84: fluid_defsfont_load_all_sampledata (fluid_defsfont.c:379)
==9970==    by 0x4E58236: fluid_defsfont_load (fluid_defsfont.c:478)
==9970==    by 0x4E57890: fluid_defsfloader_load (fluid_defsfont.c:105)
==9970==    by 0x4E74EF4: fluid_synth_sfload (fluid_synth.c:4503)
==9970==    by 0x403328: main (fluidsynth.c:771)
==9970== 
==9970== 187,680 bytes in 2,346 blocks are still reachable in loss record 191 of 192
==9970==    at 0x4C2E01F: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==9970==    by 0x4E600D4: new_samplecache_entry (fluid_samplecache.c:195)
==9970==    by 0x4E5FE21: fluid_samplecache_load (fluid_samplecache.c:92)
==9970==    by 0x4E57DD5: fluid_defsfont_load_sampledata (fluid_defsfont.c:312)
==9970==    by 0x4E57F84: fluid_defsfont_load_all_sampledata (fluid_defsfont.c:379)
==9970==    by 0x4E58236: fluid_defsfont_load (fluid_defsfont.c:478)
==9970==    by 0x4E57890: fluid_defsfloader_load (fluid_defsfont.c:105)
==9970==    by 0x4E74EF4: fluid_synth_sfload (fluid_synth.c:4503)
==9970==    by 0x403328: main (fluidsynth.c:771)
==9970== 
==9970== 342,593,540 bytes in 2,346 blocks are still reachable in loss record 192 of 192
==9970==    at 0x4C2E01F: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==9970==    by 0x4E5FCD6: fluid_sffile_read_vorbis (fluid_sffile.c:2618)
==9970==    by 0x4E5B69D: fluid_sffile_read_sample_data (fluid_sffile.c:489)
==9970==    by 0x4E60202: new_samplecache_entry (fluid_samplecache.c:222)
==9970==    by 0x4E5FE21: fluid_samplecache_load (fluid_samplecache.c:92)
==9970==    by 0x4E57DD5: fluid_defsfont_load_sampledata (fluid_defsfont.c:312)
==9970==    by 0x4E57F84: fluid_defsfont_load_all_sampledata (fluid_defsfont.c:379)
==9970==    by 0x4E58236: fluid_defsfont_load (fluid_defsfont.c:478)
==9970==    by 0x4E57890: fluid_defsfloader_load (fluid_defsfont.c:105)
==9970==    by 0x4E74EF4: fluid_synth_sfload (fluid_synth.c:4503)
==9970==    by 0x403328: main (fluidsynth.c:771)
==9970== 
==9970== LEAK SUMMARY:
==9970==    definitely lost: 48 bytes in 1 blocks
==9970==    indirectly lost: 195 bytes in 9 blocks
==9970==      possibly lost: 42,626 bytes in 1,300 blocks
==9970==    still reachable: 342,964,202 bytes in 9,545 blocks
==9970==         suppressed: 0 bytes in 0 blocks
==9970== 

[ReinholdH]

Just an additional comment:
For sf3 soundfont each individual sample is loaded individually in fluid_defsfont_load_all_sampledata. But when unloading a sf3 file, just the large sample block is deleted from the samplecache like for a sf2 soundfont. The solution has to be - similar to loading - that each sample needs to be unloaded individually from the samplecache and the memory of each individual sample needs to be released with FLUID_FREE.

Based on fluidsynth 2.0.1 I was only able to create a quick and dirty fix which I sent to "derselbst". The fix is in fluid_defsfont.h, fluid_defsfont.c. The final solution needs to be more verbose because unloading of a sf3 file is different now than unloading of a sf2 file. The information "if(sf3_file)" needs to be preserved from loading to unloading. I recommend not to open the sf3 file again just for this information but save this information accordingly.

[mawe42]

We could unload the individual samples in delete_fluid_defsfont if their sample->data pointer is different to the defsfont->sampledata pointer. For bulk loaded SF2, they are always identical, for SF3 they always differ.

[mawe42]

So basically something like this should already be enough:

diff --git a/src/sfloader/fluid_defsfont.c b/src/sfloader/fluid_defsfont.c
index ae8a9fb2..0a812770 100644
--- a/src/sfloader/fluid_defsfont.c
+++ b/src/sfloader/fluid_defsfont.c
@@ -246,7 +246,16 @@ int delete_fluid_defsfont(fluid_defsfont_t *defsfont)
 
     for(list = defsfont->sample; list; list = fluid_list_next(list))
     {
-        delete_fluid_sample((fluid_sample_t *) fluid_list_get(list));
+        sample = (fluid_sample_t *) fluid_list_get(list);
+
+        /* If the sample data pointer is different to the sampledata chunk of
+         * the soundfont, then the sample has been loaded individually (SF3)
+         * and needs to be unloaded explicitly. */
+        if (sample->data && sample->data != defsfont->sampledata)
+        {
+            fluid_samplecache_unload(sample->data);
+        }
+        delete_fluid_sample(sample);
     }
 
     if(defsfont->sample)

[mawe42]

Added a PR that implements this idea. A check with valgrind shows that it actually fixes the memory-leak.

[ReinholdH]

I tested the fix in our app and it solves the problem. Thank you.

[derselbst]

Thank you @ReinholdH for the report and @mawe42 for the fix!