Re: [bdbxml] couldn't open container twice

On Jul 22, 2005, at 11:19 PM, Dmitriy Kargapolov wrote:

> Dmitriy Kargapolov <xoid@...> writes:
>
>
>>
>> I tried to open container from two different accounts at the same  
>> time:
>>
>> envsContainer = theMgr.openContainer(txn, "test.dbxml", config);
>> pause();
>>
>> when user1 opened container, user2 couldn't open _same_ container.
>> once user1 closed container, user2 went ahead with no further  
>> problems.
>>
>> I thought container could be opened multiple times but it didn't  
>> work.
>>
>> Did anybody have similar problem?
>> Thanks.
>>
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>
> Another consideration:
> I ran two identical processes on same db/container.
> Each process opens container, performs some modification, then  
> closes it.
> Everything is done with transaction support.
> After couple minutes of normal processing both proc. are stuck.
> Backtrace in the GDB shows same place where they are waiting:
> __db_tas_mutex_lock():


When using multiple processes, you can't use the default db_env.  You  
have to open one
explicitly and pass it to the manager.  The first process needs to  
open the environment with
DB_INIT_LOCK, DB_INIT_LOG, and DB_INIT_TRANSACTION (and any other  
flags you think appropriate; I always use DB_RECOVER as well, as it  
makes things a good deal more
robust).  Subsequent processes must open the environment with only  
the DB_JOINENV
flag.
If you're still having locking issues after doing that, read the  
section on locking in the
DB Programmer's Manual. It's part of the html docs which are included  
with the DbXml download.

Good Luck.

Regards,
John Ralls