Subject Re: [firebird-support] Re: UDF and server crashes on linux
Author Tomasz Tyrakowski
On 03.05.2017 o 09:28, hvlad@... [firebird-support] wrote:
> ---In, <michkurc@...> wrote :
> Tested on FB 2.5.7 and 3.02 ubuntu_x64 14.04 (two different machines);
> On windows fbx64 works ok.
> udf return integer by value.
> scenario:
> more than 2 connections to db
> sql : select count(*) from table where validfield(field) = 1 on each connection
> table with > 2 milions record
> udf written in object pascal ( no memory leaks and other problems)
> other implementation this udf in C++ works fine on linux and windows...
> stacktrace:
> [Thread 0x7fa737789700 (LWP 28692) exited]
> [New Thread 0x7fa737789700 (LWP 28693)]
> [New Thread 0x7fa736dd7700 (LWP 28694)]
> [New Thread 0x7fa73603f700 (LWP 28698)]
> An unhandled exception occurred at $00007FA736178E2C:
> EStackOverflow: Stack overflow
> This is object pascal exception, not Firebird's one.
> Start isql, connect in embedded (aka local) mode, attach gdb to the process and run
> query with problem UDF. It should help you to find a real reason of the issue.
> Regards,
> Vlad

If Vlad's suggestion doesn't help (it definitely should, unless you're
not familiar with gdb), the first thing I'd do is to extract the
problematic function from the UDF, put it into a simple app and test
with different inputs if it actually works (the stack overflow exception
suggests there might be something wrong with the algorithm, like unbound
recursion or an infinite loop; I know you wrote "no memory leaks and
other problems", I would only add "that I'm aware of" ;) ). Also,
assuming you're compiling the UDF with FPC (free pascal), take into
account some multithreading specifics related to free pascal (take a
look at
), in particular remember to include cthreads and cmem units in your
uses list on linux. Keep in mind that superserver and superclassic
flavors of FB are multithreaded, so your UDF is in fact being loaded
into a multithreaded process, even if the UDF doesn't do any
multithreading itself.

have a good one

__--== Tomasz Tyrakowski ==--__
__--== SOL-SYSTEM ==--__
__--== ==--__