Re: Multiple threads and mdb_dbi

Let me rephrase and see if I understand correctly.

1. If I have 10 threads (but only one database), then I would need to create 10 dbi handles to the same DB and then use them as required from each thread making sure no two threads share the same DBI handle?

2. Inside each thread, I would open a new transaction (as required for the then relevant/appropriate read/write operation), but I would use a DBI handle obtained in the main thread even though that DBI was created using a different transaction handle that the one we are about to use for the current thread?

Thanks
--

Harry

On Thu, Sep 11, 2014 at 4:35 PM, Howard Chu <hyc@symas.com> wrote:

Harry B wrote:

Hello,

As per the documentation here
http://symas.com/mdb/doc/group__mdb.html#gac08cad5b096925642ca359a6d6f0562a
I see the following,

"This function must not be called from multiple concurrent transactions. A
transaction that uses this function must finish (either commit or abort)
before any other transaction may use this function."

This seems to imply that after one txn has begun on an environment, I cannot
create another txn or dbi until the first one has finished - that doesn't seem
to be right.

If I have multi-threaded app, what is the expected sequence for creation of
Environment, Transaction, and DBI handles?

Before starting any other threads:
Create the environment.
Open a transaction.
Open all DBI handles the app will need.
Commit the transaction.

After that use the DBI handles freely among any transactions/threads.

Any help is appreciated.
--
Harry

--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/

--
Harry

Re: Multiple threads and mdb_dbi_open