nginx cache exceeded, cache manager busy

[zls]

Our nginx -V outputs:

nginx: nginx version: nginx/1.0.0
nginx: built by gcc 4.1.2 20080704 (Red Hat 4.1.2-48)
nginx: TLS SNI support disabled
nginx: configure arguments:
--with-pcre=/home/ashtray/build_nginx/pcre-8.12
--add-module=/home/ashtray/build_nginx/ngx_cache_purge-1.2
--with-http_stub_status_module --with-http_ssl_module --with-debug
--prefix=/usr/local/nginx --with-http_realip_module

we have core dumps almost everyday, this happens from 0.8.15. We tried
to disable module cache_purge (but deleting the cached file outside of
nginx using rm when needed), and the worker still cores.

[xxx nginx]# ls -lhtr core/
total 69G
-rw------- 1 nobody nobody  888M Apr 26 07:23 core.32104
-rw------- 1 nobody nobody  1.1G Apr 26 09:36 core.32102
-rw------- 1 nobody nobody  1.3G Apr 26 20:38 core.32103
-rw------- 1 nobody nobody  1.3G Apr 28 22:13 core.4659
-rw------- 1 nobody nobody  1.3G Apr 28 23:53 core.9502
-rw------- 1 nobody nobody 1011M May  6 02:27 core.26681
-rw------- 1 nobody nobody  985M May  6 02:27 core.26688
-rw------- 1 nobody nobody  1.2G May  6 20:02 core.7113
-rw------- 1 nobody nobody  1.2G May  7 23:14 core.1774
-rw------- 1 nobody nobody  1.2G May  8 00:22 core.26687
-rw------- 1 nobody nobody  1.1G May  8 02:31 core.26683
-rw------- 1 nobody nobody  991M May  8 10:01 core.26346
-rw------- 1 nobody nobody  969M May 10 10:23 core.15038
-rw------- 1 nobody nobody  1.1G May 12 20:44 core.30863
-rw------- 1 nobody nobody  962M May 13 02:57 core.30860
-rw------- 1 nobody nobody  1.1G May 15 12:58 core.30861
-rw------- 1 nobody nobody  873M May 16 06:42 core.30858
-rw------- 1 nobody nobody  1.2G May 18 00:11 core.15061
-rw------- 1 nobody nobody  1.1G May 18 13:43 core.15065
-rw------- 1 nobody nobody  1.2G May 19 21:18 core.18918
-rw------- 1 nobody nobody  1.1G May 20 00:03 core.18917
-rw------- 1 nobody nobody  1.1G May 20 01:54 core.18921
-rw------- 1 nobody nobody  994M May 22 08:06 core.27758
-rw------- 1 nobody nobody  1.2G May 22 14:02 core.27754
-rw------- 1 nobody nobody  857M May 23 07:23 core.24189
-rw------- 1 nobody nobody  1.2G May 23 22:11 core.27760
-rw------- 1 nobody nobody  1.2G May 23 22:11 core.27753
-rw------- 1 nobody nobody  1.1G May 25 01:24 core.12213
-rw------- 1 nobody nobody  1.1G May 25 15:05 core.24518
-rw------- 1 nobody nobody  1.1G May 26 13:44 core.28284
-rw------- 1 nobody nobody  1.1G May 28 11:15 core.25958
-rw------- 1 nobody nobody  1.1G May 29 10:28 core.25988
-rw------- 1 nobody nobody  1.1G May 30 11:34 core.25989
-rw------- 1 nobody nobody  1.2G May 30 21:33 core.25310
-rw------- 1 nobody nobody  1.2G May 30 22:52 core.13874
-rw------- 1 nobody nobody  1.1G Jun  1 00:45 core.25148
-rw------- 1 nobody nobody  1.1G Jun  1 13:20 core.25152
-rw------- 1 nobody nobody  1.1G Jun  1 13:47 core.25149
-rw------- 1 nobody nobody  1.1G Jun  1 16:08 core.10719
-rw------- 1 nobody nobody  1.2G Jun  1 21:47 core.15534
-rw------- 1 nobody nobody  1.2G Jun  3 19:23 core.4725
-rw------- 1 nobody nobody  1.2G Jun  3 22:32 core.5872
-rw------- 1 nobody nobody  1.2G Jun  4 00:05 core.4718
-rw------- 1 nobody nobody  1.1G Jun  4 00:30 core.4723
-rw------- 1 nobody nobody  1.1G Jun  4 05:31 core.4719
-rw------- 1 nobody nobody  1.1G Jun  4 18:45 core.29156
-rw------- 1 nobody nobody  1.2G Jun  4 18:56 core.29157
-rw------- 1 nobody nobody  1.2G Jun  4 20:32 core.29160
-rw------- 1 nobody nobody  1.2G Jun  4 20:32 core.29158
-rw------- 1 nobody nobody  1.2G Jun  4 20:32 core.29155
-rw------- 1 nobody nobody  1.2G Jun  4 22:32 core.29996
-rw------- 1 nobody nobody  1.2G Jun  4 23:08 core.29989
-rw------- 1 nobody nobody  1.2G Jun  6 01:07 core.20367
-rw------- 1 nobody nobody  970M Jun  6 05:44 core.20366
-rw------- 1 nobody nobody  1.2G Jun  6 16:46 core.20369
-rw------- 1 nobody nobody  1.2G Jun  6 16:46 core.20368
-rw------- 1 nobody nobody  1.2G Jun  6 17:16 core.20365
-rw------- 1 nobody nobody  1.2G Jun  6 18:04 core.16095
-rw------- 1 nobody nobody  1.1G Jun  7 03:15 core.20363
-rw------- 1 nobody nobody  987M Jun  7 03:16 core.28162
-rw------- 1 nobody nobody  1.1G Jun  7 10:35 core.28252
-rw------- 1 nobody nobody  1.1G Jun  7 10:57 core.10354
-rw------- 1 nobody nobody  1.1G Jun  7 11:45 core.10352
-rw------- 1 nobody nobody  773M Jun  8 05:47 core.14587

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,182995,204866#msg-204866