Randomly lost connection errors

Discussion of open issues, suggestions and bugs regarding usage of dbExpress drivers for MySQL in Delphi and C++Builder
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CristianP
Posts: 69
Joined: Fri 07 Dec 2012 07:44
Location: Timișoara, Romania

Randomly lost connection errors

Post by CristianP » Fri 07 Dec 2012 09:16

Hi,

I changed from 5.1.2 to 6.0.1 (with XE2) and tested to three customers. Each of them has 20-40 computers in network. With 6.0.1 there is one or two computer in each network with connection errors like these two.
The errors occur randomly after tens of successfully executions. Then other tens successfully and again errors.
I changed back to 5.1.2 only on these computers and all is normal now. Of course with my application recompiled with 5.1.2.

Best Regards,
Cristian Peta

exception class : TDBXError
exception message : Lost connection to MySQL server during query Socket error on write. WSAGetLastError return 10054($2746).

main thread ($7fc):
008895d9 +051 WinArhi.exe Data.DBXCommon 11134 +8 TDBXContext.Error
00b40956 +10a WinArhi.exe Data.DBXDynalink 826 +21 TDBXMethodTable.RaiseError
00b40fa7 +013 WinArhi.exe Data.DBXDynalink 992 +1 TDBXDynalinkConnection.CheckResult
00b40f76 +01e WinArhi.exe Data.DBXDynalink 972 +1 TDBXDynalinkConnection.CreateAndBeginTransaction


exception class : EOleException
exception message : Can't connect to MySQL server on '192.168.121.2' (10061) Socket error on connect. WSAGetLastError return 10060($274C).

main thread ($1510):
006b534d +0c1 WinArhi.exe Datasnap.DBClient 4677 +6 TCustomClientDataSet.DoGetRecords
006ac25f +1b7 WinArhi.exe Datasnap.DBClient 1147 +25 TCustomClientDataSet.OpenCursor
005173a9 +055 WinArhi.exe Data.DB 11314 +12 TDataSet.SetActive

AndreyZ

Re: Randomly lost connection errors

Post by AndreyZ » Fri 07 Dec 2012 11:30

Hello,

To investigate this problem, I need a test project that demonstrates it. Please try creating such project and send it to andreyzATdevartDOTcom . Also, please specify the exact version of MySQL server you are using.

CristianP
Posts: 69
Joined: Fri 07 Dec 2012 07:44
Location: Timișoara, Romania

Re: Randomly lost connection errors

Post by CristianP » Wed 12 Dec 2012 08:58

Hallo,

I can not reproduce the errors on my system.
The errors have occurred exactly after update to the new drivers on customer computers. But now I tested again and on two computers the errors has gone.
There is left only one computer to test again and I hope today.
Sorry for disturbance.

Best regards,
Cristian Peta

AndreyZ

Re: Randomly lost connection errors

Post by AndreyZ » Thu 13 Dec 2012 10:11

If any other questions come up, please contact us.

CristianP
Posts: 69
Joined: Fri 07 Dec 2012 07:44
Location: Timișoara, Romania

Re: Randomly lost connection errors

Post by CristianP » Fri 14 Dec 2012 13:33

Hi,

I tested on last computer and I can reproduce easily.
I tried with 6.0.1 and again with 5.1.2 more times.
With 5.1.2 all is OK.
With 6.0.1 in dbMonitor one time I see nothing, second test it was four executions before lost connection. BTW lost connection do not appear in dbMonitor.

MySQL server is in WAN. Ping with 49-51ms. Trace route with one time out in the middle of the list.
Next time I will have access I will install MySQL on this computer and try again with localhost to see if the problem is network or something on this system.
Any suggestions what else to try?

Best Regards,
Cristian Peta

AndreyZ

Re: Randomly lost connection errors

Post by AndreyZ » Tue 18 Dec 2012 10:19

Please try creating a small sample to demonstrate the problem and send it to andreyz*devart*com . Also please specify the following:
- the exact version of MySQL server you are using;
- the exact version of Windows (XP, Vista, etc.) on the computer where you reproduced the problem.

CristianP
Posts: 69
Joined: Fri 07 Dec 2012 07:44
Location: Timișoara, Romania

Re: Randomly lost connection errors

Post by CristianP » Tue 15 Jan 2013 10:08

Hallo,

only today I have confirmation that with 6.1.2 (with XE2) the errors has gone.
Anyway I use 5.1.2 in XE2.
For XE3 and my future program versions I changed to UniDAC.
It seems that it was the same cause like "Error with temporary table".

Best Regards,
Cristian Peta

AndreyZ

Re: Randomly lost connection errors

Post by AndreyZ » Tue 15 Jan 2013 16:27

It is very likely that random connection lost errors you encountered in version 6.0.1 have the same cause as the error with temporary tables.
Thank you for your confirmation that random connection lost errors are solved in 6.1.2.

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