Hi Sergey,

> I'm afraid fixing rnd_end() callers in the server may stall for a long time.

O.K. No need to fix it if it is not easy. This request is not high priority request.

> Is it accaptable for spider to use bulk updates and deletes API instead

> (see handler.h: start_bulk_update/start_bulk_delete).

Spider use it already. This API is not used if target table has after trigger. I understand why this API is not used in this case, but it sometimes causes performance problem. So, I thought it is better to prepare other choice for something wrong. Anyway, I will disable bulk updating/deleting feature without using API.

> Nope, it looks like a bug in thread pool. MDEV-4739 has different trace, how

did you get this one? Just executed given test?

I got this trace when I try to reproduce MDEV-4739. I did as the followings.

1. start mysqld

2. log in mysqld

3. mysql> CREATE TABLE t1 (a INT) ENGINE=InnoDB;

4. mysql> XA START 'xa1';

5. mysql> INSERT INTO t1 (a) VALUES (1),(2);

6. mysql> XA END 'xa1';

7. mysql> XA PREPARE 'xa1';

8. kill -9 mysqld_safe and mysqld from another terminal

9. start mysqld on gdb

At that time, InnoDB and Spider were enabled and log-bin was disabled. So probably "total_ha_2pc > 1" was true, "opt_bin_log" was false.

Does it help you?

Thanks,

Kentoku

2013/9/19 Sergey Vojtovich <svoj@mariadb.org>

Hi Kentoku,

I'm adding MariaDB developers to CC.

On Thu, Sep 19, 2013 at 01:19:13AM +0900, kentoku wrote:
> Hi Sergey,
>
> > But what kind of errors are possible in your case? Other storage engines
> doesn't
> seem to suffer from this API violation.
>
> Spider support bulk updating and deleting for avoiding network roundtrip
> between data node. Some times, last bulk updating is executed in rnd_end()
> function. So rnd_end() has possibility getting errors from data node.
I'm afraid fixing rnd_end() callers in the server may stall for a long time.
Is it accaptable for spider to use bulk updates and deletes API instead
(see handler.h: start_bulk_update/start_bulk_delete).

> By the way, about MDEV-4739. I get the following stack trace.
> Program received signal SIGSEGV, Segmentation fault.
> 0x00000000005eabf6 in thd_wait_begin (thd=0x29da060,
> wait_type=10)
> at /ssd1/mariadb-10.0.4/sql/sql_class.cc:4277
> 4277 MYSQL_CALLBACK(thd->scheduler, thd_wait_begin, (thd, wait_type));
> (gdb) print thd
> $1 = (THD *) 0x29da060
> (gdb) bt
> #0 0x00000000005eabf6 in thd_wait_begin (
> thd=0x29da060, wait_type=10)
> at /ssd1/mariadb-10.0.4/sql/sql_class.cc:4277
> #1 0x000000000072a114 in scheduler_wait_sync_begin ()
> at /ssd1/mariadb-10.0.4/sql/scheduler.cc:59
> #2 0x0000000000d6dc20 in my_sync (fd=23, my_flags=0)
> at /ssd1/mariadb-10.0.4/mysys/my_sync.c:76
> #3 0x0000000000d6b54f in my_msync (fd=23,
> addr=0x7ffff7ff4000, len=4096, flags=4)
> at /ssd1/mariadb-10.0.4/mysys/my_mmap.c:27
> #4 0x00000000008bea03 in TC_LOG_MMAP::open (
> this=0x16e6a00, opt_name=0xe19c87 "tc.log")
> at /ssd1/mariadb-10.0.4/sql/log.cc:7735
> #5 0x00000000005751cb in init_server_components ()
> at /ssd1/mariadb-10.0.4/sql/mysqld.cc:4797
> #6 0x0000000000575a07 in mysqld_main (argc=30,
> argv=0x1f204d0)
> at /ssd1/mariadb-10.0.4/sql/mysqld.cc:5208
> #7 0x000000000056d884 in main (argc=11,
> argv=0x7fffffffe3a8)
> at /ssd1/mariadb-10.0.4/sql/main.cc:25
> (gdb) print thd->scheduler
> $2 = (scheduler_functions *) 0x8f8f8f8f8f8f8f8f
> (gdb) print thd_wait_begin
> $3 = {void (THD *,
> int)} 0x5eaba4 <thd_wait_begin(THD*, int)>
> (gdb) print wait_type
> $4 = 10
>
> It is looks that "thd->scheduler" is not initialized. What do you think?
> Must storage engine set it?
Nope, it looks like a bug in thread pool. MDEV-4739 has different trace, how
did you get this one? Just executed given test?

Regards,
Sergey