GMAN_DO always returns NULL

[Swany]

mysql> select gman_servers_set('127.0.0.1:7001');
+------------------------------------+
| gman_servers_set('127.0.0.1:7001') |
+------------------------------------+
| 127.0.0.1:7001 |
+------------------------------------+
1 row in set (0.00 sec)

mysql> select gman_do('shard_query_worker','{"sql":"show databases","schema_name":"default"}');
+----------------------------------------------------------------------------------+
| gman_do('shard_query_worker','{"sql":"show databases","schema_name":"default"}') |
+----------------------------------------------------------------------------------+
| NULL |
+----------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Gearman has 'shard_query_worker' workers waiting for jobs:
status
custom_function 0 0 72
shard_query_worker 0 0 24
loader 1164 24 24
store_resultset 0 0 24
.

I don't know why GMAN_DO is returning NULL. No error messages are written to the log.

[Swany (greenlion)]

I tried MySQL 5.5, MariaDB 5.5, MySQL 5.6 all have same behavior on this box.
# uname -a
Linux bm-smtwin-b01 3.13.0-33-generic #58-Ubuntu SMP Tue Jul 29 16:45:05 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

[Swany (greenlion)]

This appears to be a problem with ubuntu libgearman-dev package. When I compiled my own gearmand and pointed configure to it, the issue resolved itself.

So probably not a gearman-mysql-udf bug, sorry.

[cam (green-field)]

"This appears to be a problem with ubuntu libgearman-dev package. When I compiled my own gearmand and pointed configure to it, the issue resolved itself."

how to do,please!