Re: [BUGS] Random hang during commit

#1

Lin, B (Bill) wrote:

Quote:

After upgrade from postgres 8.0 to 8.1.3, I am running some tests
against the new database and got some random problems:
Usually all tests are successfully passed, but sometime the test hangs
when doing connection.commit().

Some more information please.
1. What operating-system?
2. Installed from a package (which) or source?
3. What hangs - the client or the backend (or both)?
4. What do the logs show?

--
Richard Huxton
Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?

http://archives.postgresql.org

#2

Bill - please cc: the bugs list too.

Lin, B (Bill) wrote:

Quote:

Some more information please.
1. What operating-system?
XP SP2
2. Installed from a package (which) or source?
From package
3. What hangs - the client or the backend (or both)?
Both. The client is waiting for the backend's commit() to be completed.
4. What do the logs show?
Usually, the last log shows commit is executed.

Hmm - if the log shows the commit happening that suggests the backend is
doing its bit. It's not hanging, it's just idle waiting for the next
query from the client. That would mean that the problem is either in the
client library, jdbc driver or the communication channel itself.

In your original message, you say: "I have installed same database, jdbc
driver, jre and test case on some other computers. However, this problem
will be never happened on others."

Does that mean 8.1.3 works fine on other PCs you have, but not this one?

If so, that suggests to me that there must be either:
1. A different library on the problem machine.
2. Some process (firewall/antivirus) that is occasionally interfering
with communication.

Three things suggest themselves to me:
1. Make sure there aren't any known issues with the jdbc driver version
you have http://jdbc.postgresql.org/
2. Check if there is anything unusual about the problem machine
3. Try running the client on the problem machine and the database on
another, then the other way around. Does this change anything?

--
Richard Huxton
Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend

#3

Quote:

Does that mean 8.1.3 works fine on other PCs you have, but not this
one?

Yes, it is works fine with other PCs which do not have dual processor.
(I can not find another machine has dual processor here)

Quote:

If so, that suggests to me that there must be either:
1. A different library on the problem machine.
No, same library are used.
2. Some process (firewall/antivirus) that is occasionally interfering
with communication.

No firewall/antivirus was running

Quote:

Three things suggest themselves to me:
1. Make sure there aren't any known issues with the jdbc driver version
you have http://jdbc.postgresql.org/

Seems not, but not sure about this one:
http://jdbc.postgresql.org/todo.html#Known+Bugs
[bugs] Deallocating large numbers of server side statements can break
the connection by filling network buffers. This is a very, very low
probability bug, but it is still possible.

Actually, if using jdbc driver version 7.4 against database 8.1.3, this
problem will not happen.
It seems it is a bug relate with jdbc driver for a dual processor.

Quote:

2. Check if there is anything unusual about the problem machine
Nothing unusual
3. Try running the client on the problem machine and the database on
another, then the other way around. Does this change anything?

I tried both way and this problem seems never happen.

-----Original Message-----
From: Richard Huxton [mailto:dev (AT) archonet (DOT) com]
Sent: 14 March 2006 09:22
To: Lin, B (Bill)
Cc: pgsql-bugs (AT) postgresql (DOT) org
Subject: Re: [BUGS] Random hang during commit

Bill - please cc: the bugs list too.

Lin, B (Bill) wrote:

Quote:

Some more information please.
1. What operating-system?
XP SP2
2. Installed from a package (which) or source?
From package
3. What hangs - the client or the backend (or both)?
Both. The client is waiting for the backend's commit() to be
completed.
4. What do the logs show?
Usually, the last log shows commit is executed.

Hmm - if the log shows the commit happening that suggests the backend
is doing its bit. It's not hanging, it's just idle waiting for the next

query from >the client. That would mean that the problem is either in
the client library, jdbc driver or the communication channel itself.

Quote:

In your original message, you say: "I have installed same database,
jdbc driver, jre and test case on some other computers. However, this

problem will be >never happened on others."

Quote:

Does that mean 8.1.3 works fine on other PCs you have, but not this
one?

Quote:

If so, that suggests to me that there must be either:
1. A different library on the problem machine.
2. Some process (firewall/antivirus) that is occasionally interfering
with communication.

Quote:

Three things suggest themselves to me:
1. Make sure there aren't any known issues with the jdbc driver version
you have http://jdbc.postgresql.org/
2. Check if there is anything unusual about the problem machine
3. Try running the client on the problem machine and the database on
another, then the other way around. Does this change anything?

--
Richard Huxton
Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?

http://archives.postgresql.org

#4

Lin, B (Bill) wrote:

Quote:

Does that mean 8.1.3 works fine on other PCs you have, but not this
one?
Yes, it is works fine with other PCs which do not have dual processor.
(I can not find another machine has dual processor here)

Ah, does your problem match what is being discussed here?
http://archives.postgresql.org/pgsql...3/msg00032.php

Quote:

If so, that suggests to me that there must be either:
1. A different library on the problem machine.
No, same library are used.
2. Some process (firewall/antivirus) that is occasionally interfering
with communication.
No firewall/antivirus was running

Three things suggest themselves to me:
1. Make sure there aren't any known issues with the jdbc driver version
you have http://jdbc.postgresql.org/
Seems not, but not sure about this one:
http://jdbc.postgresql.org/todo.html#Known+Bugs
[bugs] Deallocating large numbers of server side statements can break
the connection by filling network buffers. This is a very, very low
probability bug, but it is still possible.

Hmm - doesn't sound like that's it.

Quote:

Actually, if using jdbc driver version 7.4 against database 8.1.3, this
problem will not happen.
It seems it is a bug relate with jdbc driver for a dual processor.

Or possibly lower down even.

Quote:

2. Check if there is anything unusual about the problem machine
Nothing unusual
3. Try running the client on the problem machine and the database on
another, then the other way around. Does this change anything?
I tried both way and this problem seems never happen.

Hmm - I'd have expected it to fail in one direction but not the other.
--
Richard Huxton
Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster

#5

Yes, It looks exactly same as
http://archives.postgresql.org/pgsql...3/msg00032.php
Only different is: in my case it happens in every 2 mins

(I just found it is not only happen during commit, it could be during
other sql call randomly)

Thank you very much, at least I know what is the problem now.

Bill

-----Original Message-----
From: Richard Huxton [mailto:dev (AT) archonet (DOT) com]
Sent: 15 March 2006 11:27
To: Lin, B (Bill)
Cc: pgsql-bugs (AT) postgresql (DOT) org
Subject: Re: [BUGS] Random hang during commit

Lin, B (Bill) wrote:

Quote:

Does that mean 8.1.3 works fine on other PCs you have, but not this
one?
Yes, it is works fine with other PCs which do not have dual processor.
(I can not find another machine has dual processor here)

Ah, does your problem match what is being discussed here?
http://archives.postgresql.org/pgsql...3/msg00032.php

Quote:

If so, that suggests to me that there must be either:
1. A different library on the problem machine.
No, same library are used.
2. Some process (firewall/antivirus) that is occasionally interfering
with communication.
No firewall/antivirus was running

Three things suggest themselves to me:
1. Make sure there aren't any known issues with the jdbc driver
version
you have http://jdbc.postgresql.org/
Seems not, but not sure about this one:
http://jdbc.postgresql.org/todo.html#Known+Bugs
[bugs] Deallocating large numbers of server side statements can break
the connection by filling network buffers. This is a very, very low
probability bug, but it is still possible.

Hmm - doesn't sound like that's it.

Quote:

Actually, if using jdbc driver version 7.4 against database 8.1.3,
this problem will not happen.
It seems it is a bug relate with jdbc driver for a dual processor.

Or possibly lower down even.

Quote:

2. Check if there is anything unusual about the problem machine
Nothing unusual
3. Try running the client on the problem machine and the database on
another, then the other way around. Does this change anything?
I tried both way and this problem seems never happen.

Hmm - I'd have expected it to fail in one direction but not the other.
--
Richard Huxton
Archonet Ltd

---------------------------(end of broadcast)---------------------------
TIP 5: don't forget to increase your free space map settings

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Re: [BUGS] Random hang during commit

mailing.database.pgsql-bugs mailing.database.pgsql-bugs

Re: [BUGS] Random hang during commit - 03-13-2006 , 12:41 PM

Re: [BUGS] Random hang during commit - 03-14-2006 , 03:36 AM

Re: [BUGS] Random hang during commit - 03-15-2006 , 04:58 AM

Re: [BUGS] Random hang during commit - 03-15-2006 , 05:49 AM

Re: [BUGS] Random hang during commit - 03-15-2006 , 05:56 AM