php慢日志总有+++ dump failed错误

Question

php慢日志总有+++ dump failed错误，网上搜索了一圈也没找到答案，希望得到大家指点。

详细日志如下 ：
[17-Dec-2015 16:28:30] [pool www] pid 29220
script_filename = /var/tt/mm.php
[0x00000000023b6990] curl_exec() /var/tt/my.php:20
[0x00000000023b5088] http_request_json() /var/tt/mm/login.php:75
[0x00000000023b4a20] +++ dump failed

[17-Dec-2015 16:29:54] [pool www] pid 29544
script_filename = /var/tt/mm_reg.php
[0x00000000022231c0] curl_exec() /var/tt/my.php:20
[0x0000000002220ae0] http_request_json() /var/tt/mm_reg.php:235

[17-Dec-2015 16:36:19] [pool www] pid 20815
script_filename = /var/tt/mm_reg.php
[0x00000000023b7160] curl_exec() /var/tt/my.php:20
[0x00000000023b4a80] http_request_json() /var/tt/mm_reg.php:235

[17-Dec-2015 16:48:46] [pool www] pid 27734
script_filename = /var/tt/mm.php
[0x00000000023b69f0] curl_exec() /var/tt/my.php:20
[0x00000000023b50e8] http_request_json() /var/tt/mm/login.php:75
[0x00000000023b4a80] +++ dump failed

[17-Dec-2015 17:02:26] [pool www] pid 3215
script_filename = /var/tt/mm_reg.php
[0x0000000002370800] curl_exec() /var/tt/my.php:20
[0x000000000236e120] http_request_json() /var/tt/mm_reg.php:235

[17-Dec-2015 17:08:39] [pool www] pid 5503
script_filename = /var/tt/mm.php
[0x00000000023a87a0] curl_exec() /var/tt/my.php:20
[0x00000000023a6e98] http_request_json() /var/tt/mm/login.php:75
[0x00000000023a6830] +++ dump failed

[17-Dec-2015 17:12:04] [pool www] pid 6592
script_filename = /var/tt/mm.php
[0x00000000023b69f0] curl_exec() /var/tt/my.php:20
[0x00000000023b50e8] http_request_json() /var/tt/mm/login.php:75
[0x00000000023b4a80] +++ dump failed

[17-Dec-2015 17:31:51] [pool www] pid 19806
script_filename = /var/tt/mm_reg.php
[0x00000000023707d0] curl_exec() /var/tt/my.php:20
[0x000000000236e0f0] http_request_json() /var/tt/mm_reg.php:235
[root@iZ286xgh6itZ log]# +++ dump failed