Aaron Weiss writes:
> Hi,
>
> I wanted to create a UDF for MySQL that can use the ASpell engine to
> generate a string of spelling suggestions, given a single word
> parameter. Thus, select aspell('wrd') should return Aspell's suggested
> spellings.
>
> I don't know C very well at all, so I began using an existing UDF
> function already written, called unprefix(). I changed the main
> subroutine to open a pipe to aspell, and to read the output of the
> pipe (aspell's suggestions). Because aspell sometimes returns
> a suggestions string longer than 255 character I tried to use malloc()
> to give the string a maximum headroom of 1024 characters.
>
> When I compile and create this UDF, it seems to work. Queries to it
> produce the correct results. No problems. However, in a live
> production environment where tens of these queries are sent over a
> few minutes, mysqld is repeatedly, seemingly randomly, crashing and
> restarting itself. Checking the logs, I see it is only queries using
> my new "aspell" UDF that cause the crash. However, it seems random
> because 99% of aspell queries in the log do not cause a crash, and the
> ones that do are not replicable (trying to repeat a UDF query that caused
> the crash does not cause a crash again).
>
> The more serious problem is that sometimes mysqld cannot restart
> itself (error log shows that TCP/IP port is 'in use'). That's when the
> server is effectively dead.
>
> I retrieved the stack trace information that MySQL reports during each
> crash. It is always the same stack trace info. If anyone has any hints for me as to
>what
> this is saying, maybe I can pinpoint the source of the problem. As it
> is now, I have no idea!
>
> 0x40073522 _end + 938017058
> 0x40139897 _end + 938828951
> 0x411cf9de _end + 956220894
> 0x8091dab val_str__17Item_func_udf_strP6String + 119
> 0x808a129 send__4ItemP6String + 73
> 0x80b5e8a send_data__11select_sendRt4List1Z4Item + 98
> 0x80dd236
>
>mysql_select__FP3THDP13st_table_listRt4List1Z4ItemP4ItemRt4List1Z15Item_func_matchP8st_orderT5P4ItemT5UiP13select_result
> +
> 1830
> 0x80c3467 mysql_execute_command__Fv + 783
> 0x80c7523 mysql_parse__FP3THDPcUi + 199
> 0x80c2849 do_command__FP3THD + 1157
> 0x80c1ea6 handle_one_connection__FPv + 582
>
> **crash!**
>
> thanks!
> Aaron Weiss ([EMAIL PROTECTED])
> CTO, Wordsmyth Collaboratory
> http://www.wordsmyth.net
>
>
>
Hi!
Possible cause of your problems might be that you have not made that
function thread - safe.
Regards,
Sinisa
____ __ _____ _____ ___ == MySQL AB
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