Lists

Open Menu Close Menu

Terms and Conditions
Lists hosted on this site
Email the Postmaster
Tips for posting to public mailing lists

Re: hangs in flockfile() during fread() or fclose()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: hangs in flockfile() during fread() or fclose()

Subject: Re: hangs in flockfile() during fread() or fclose()
From: "Stephen J. Butler" <email@hidden>
Date: Thu, 10 Jul 2014 00:04:04 -0500

Don't take this the wrong way, but...

Incredible claims -- like stdio being broken -- require incredible evidence. From our perspective, it's much more likely that your code has a memory corruption, double free, or stack smashing bug somewhere than stdio not working correctly. You might want to try Malloc Debug if you haven't already:

https://developer.apple.com/library/mac/documentation/performance/conceptual/managingmemory/articles/MallocDebug.html

valgrind, although a pain to setup, has also helped me find memory related bugs in the past.

Of course, a reproducible test case would point the finger where it belongs. Or it might help you find a bug in your code. I know there have been times I was ready to blame a framework for something, and when writing the test case I discovered it was something I'd misunderstood.

On Wed, Jul 9, 2014 at 11:26 PM, Paul Smith <email@hidden> wrote:

On Wed, 2014-07-09 at 19:55 -0500, Stephen J. Butler wrote:
> Can you distill this down to self contained test case?

Difficult. It only happens once in a while on our system in our test
suite which is 14,000 individual tests of our entire application.
Basically every now and then we notice that the tests are hung and when
we go to investigate and get a core this is what we find. It happens at
different times in different areas (the fclose() hang was in a totally
different function, reading different files).

Our use of stdio functions is literally as simple as the example I
quoted in my original email: the FILE* is opened and assigned to a local
variable, used, then closed before the function returns and not passed
to any functions (except other stdio functions).

I could try to write a simple program that created lots of threads and
randomly read/wrote files: not sure how effective that would be as a
repro case.

I'm wondering if someone has pointers on what we might investigate (and
how) when we get a process in this state, that might help us narrow down
where to look or what to concentrate on.

 _______________________________________________
Do not post admin requests to the list. They will be ignored.
Darwin-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:

This email sent to email@hidden

References:
	>hangs in flockfile() during fread() or fclose() (From: Paul Smith <email@hidden>)
	>Re: hangs in flockfile() during fread() or fclose() (From: "Stephen J. Butler" <email@hidden>)
	>Re: hangs in flockfile() during fread() or fclose() (From: Paul Smith <email@hidden>)

Prev by Date: Re: hangs in flockfile() during fread() or fclose()
Next by Date: Re: hangs in flockfile() during fread() or fclose()
Previous by thread: Re: hangs in flockfile() during fread() or fclose()
Next by thread: fenv not inherited from parent thread
Index(es):
- Date
- Thread