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»Forums Index »IQFeed Developer »IQFeed Developer Support »IQConnect.exe (and hangs on connect for multiple connections
Author Topic: IQConnect.exe (and hangs on connect for multiple connections (5 messages, Page 1 of 1)

-Interested User-
Posts: 12
Joined: May 11, 2014

Posted: Mar 30, 2016 03:54 AM          Msg. 1 of 5
I have come across a critical problem with the IQConnect software when establishing multiple connections in quick succession.

Steps to reproduce:
1 - launch client, login
2 - for i = 1 to 15 {
create new socket on port 9100
send set protocol command
sleep x
3 - wait
4 - close all sockets

For values of x < ~15ms, the threads for each socket in the iqconnect process seem to enter some sort of race condition, and ramp up to 100% CPU (core) usage. This will typically happen to all 15 connections, but is sometimes limited to fewer (e.g 3 IQConnect threads running at 100% on 3 cores).

During failures:
- IQConnect threads are running at 100% on all 8 cores of my machine (although sometimes fewer as mentioned above).
- There is no response on the socket to any commands sent, including the initial set protocol.
- There are no entries in the IQConnectLog after "LOOKUP SOCKET ACCEPTED i - " for each connection.

Log files are attached.


This occurs on versions and (didn't test others). I am connecting from Java using standard / libraries

OS tested:
- Debian 8 64-bit (kernel 4.5.0 x86_64)
- Debian 7 32-bit (kernel 4.5.0 x86),

JVM tested:
- 1.7.0_80-b15 (32 bit)
- 1.8.0_77 (32 and 64-bit)

Wine tested:
- 1.6.2
- 1.9.6

Interestingly, I couldn't reproduce the problem using wine 1.4.1, but I suspect that's because 1.4.1 is slower to create and connect the sockets rather than wine being the problem. This issue only became evident because I am staging newer wine versions.

I couldn't reproduce the issue with the same code on Windows 7.

I would guess that the most likely explanation is a subtle concurrency bug in the IQConnect.exe connection code that is only evident when multiple connections are made almost simultaneously on a machine with many cores, but it is surprising that it hasn't been seen before.

I can provide test code (Java) if required.

File Attached: IQConnectLogAll-fail.txt (downloaded 453 times)

-Interested User-
Posts: 12
Joined: May 11, 2014

Posted: Mar 30, 2016 04:12 AM          Msg. 2 of 5
Example screenshot showing partial (4 connections) hang.

File Attached: partial-lockup-example.png (downloaded 431 times)

-Interested User-
Posts: 6
Joined: Apr 25, 2007

-DTN Technical Support-

Posted: Mar 30, 2016 04:17 AM          Msg. 3 of 5
Thank you for your post. Developer Support will respond ASAP.

Robert Carrillo

Trading Markets Customer Service


-Interested User-
Posts: 12
Joined: May 11, 2014

Posted: Mar 30, 2016 06:34 AM          Msg. 4 of 5
For reference, here's a log of the same code running when the issue doesn't occur.

File Attached: IQConnectLogAll-succeed.txt (downloaded 482 times)

DTN_Tim Walter
-DTN Guru-
Posts: 1238
Joined: Apr 25, 2006

Posted: Mar 30, 2016 08:36 AM          Msg. 5 of 5
This was a known issue in 5.1, but we have had good results with releases since and so far on 5.2, but we will take a look into it and see what we can come up with.



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