335544364 : request synchronization error

[Tomasz Dubiel]

Hello.

Linux Firebird 2.5.7 64 bit. In one of our customers' system we face problems with state of hung application. When we traced one specific connection, we noticed such an error:

<SQL> 

...

7760 records fetched

395 ms, 14182 read(s), 310347 fetch(es)

2022-05-31T14:55:06.4940 (15935:0x7f4a79407978) ERROR AT jrd8_fetch

....

335544364 : request synchronization error

What can be a reason of this? Application written in Delphi.

[Tomasz Dubiel]

SQL executes fine, there is no problem with that.

[Mark Rotteveel]

IIRC, request synchronization error occurs if incorrect or unexpected
messages are received by the server or client. This generally indicates
a bug in the implementation of the wire protocol, but could also be a
usage error.

I would recommend first of all, upgrade to Firebird 2.5.9, and make sure
the application uses fbclient of 2.5.9 as well.

For example, 2.5.8 fixed an occurrence of a request synchronization
error during restore (the ticket isn't specific enough to see if that
was specific to gbak, or a more general problem that could apply elsewhere)

Mark
--
Mark Rotteveel

[Dimitry Sibiryakov]

Mark Rotteveel wrote 31.05.2022 15:59:
>
> IIRC, request synchronization error occurs if incorrect or unexpected messages
> are received by the server or client. This generally indicates a bug in the
> implementation of the wire protocol, but could also be a usage error.

In this case it is a "normal error", result of specific internal query
processing inside of the engine.

--
WBR, SD.

[Mark Rotteveel]

That shouldn't happen, a request synchronization is never a "normal
error" as far as I'm aware, and I'm curious to know how you come to that
conclusion that it is the case here.

Mark
--
Mark Rotteveel

[Dimitry Sibiryakov]

Mark Rotteveel wrote 31.05.2022 17:08:
> That shouldn't happen, a request synchronization is never a "normal error" as
> far as I'm aware, and I'm curious to know how you come to that conclusion that
> it is the case here.

I was told it by Vlad or Dmitry. Synchronization error in jrd8_fetch is
related to last fetched record IIRC.

--
WBR, SD.

[Tomasz Dubiel]

With Firebird 2.5.9 (it's Classic Server) and 2.5.9 fbclient the problem remains the same.

<SQL>

1472 records fetched

4049 ms, 21311 read(s), 6678588 fetch(es)

2022-06-01T09:04:08.3840 (12747:0x7fb37c8ff978) ERROR AT jrd8_fetch

.....

335544364 : request synchronization error