RE: [Haskell-cafe] Project postmortem
On 21 November 2005 10:16, Joel Reymont wrote: Is Wolfgang still around? Would you guys be willing to guide me through this? I could then possibly become the next Mac OSX expert :-). I have the disassembler dumps, etc. I do not know how to approach this problem. I read up a bit on the GHC internals, STG, code generation, etc. If anyone is interested, this turned out to be a bug in the Network.BSD module, namely that getHostByName isn't thread safe because it is based on the C library function gethostbyname(), which returns data in a single static area. Workarounds are: - do your own mutual exclusion locking around getHostByName and any function that calls it (eg. connectTo). - use Network.Alt (http://www.cs.helsinki.fi/u/ekarttun/network-alt/), which has a thread-safe implementation of getHostByName. - wait for 6.4.2, which will contain a fix for this bug (we don't have a fix committed yet, Einar Karttunen has kindly offered to look into it). Cheers, Simon ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [Haskell-cafe] Project postmortem
On Fri, Dec 02, 2005 at 11:20:54AM -, Simon Marlow wrote: If anyone is interested, this turned out to be a bug in the Network.BSD module, namely that getHostByName isn't thread safe because it is based on the C library function gethostbyname(), which returns data in a single static area. Workarounds are: - do your own mutual exclusion locking around getHostByName and any function that calls it (eg. connectTo). - use Network.Alt (http://www.cs.helsinki.fi/u/ekarttun/network-alt/), which has a thread-safe implementation of getHostByName. - wait for 6.4.2, which will contain a fix for this bug (we don't have a fix committed yet, Einar Karttunen has kindly offered to look into it). Do I understand correctly that another workaround is - don't compile your programs with -threaded ? Best regards Tomasz -- I am searching for a programmer who is good at least in some of [Haskell, ML, C++, Linux, FreeBSD, math] for work in Warsaw, Poland ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [Haskell-cafe] Project postmortem
I thought that if -threaded is not used then all the blocking IO is assigned a separate OS thread. On Dec 2, 2005, at 12:10 PM, Tomasz Zielonka wrote: Do I understand correctly that another workaround is - don't compile your programs with -threaded ? -- http://wagerlabs.com/ ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: [Haskell-cafe] Project postmortem
On 02 December 2005 12:11, Tomasz Zielonka wrote: On Fri, Dec 02, 2005 at 11:20:54AM -, Simon Marlow wrote: If anyone is interested, this turned out to be a bug in the Network.BSD module, namely that getHostByName isn't thread safe because it is based on the C library function gethostbyname(), which returns data in a single static area. Workarounds are: - do your own mutual exclusion locking around getHostByName and any function that calls it (eg. connectTo). - use Network.Alt (http://www.cs.helsinki.fi/u/ekarttun/network-alt/), which has a thread-safe implementation of getHostByName. - wait for 6.4.2, which will contain a fix for this bug (we don't have a fix committed yet, Einar Karttunen has kindly offered to look into it). Do I understand correctly that another workaround is - don't compile your programs with -threaded ? No, the bug isn't related to -threaded. It still occurs without -threaded. Cheers, Simon ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [Haskell-cafe] Project postmortem
On Fri, Dec 02, 2005 at 12:39:25PM -, Simon Marlow wrote: Do I understand correctly that another workaround is - don't compile your programs with -threaded ? No, the bug isn't related to -threaded. It still occurs without -threaded. Let's check that now I understand - so the sequence call gethostbyname read the returned hostent is written in Haskell, and many such sequences can be interleaved when using Concurrent Haskell? Best regards Tomasz -- I am searching for a programmer who is good at least in some of [Haskell, ML, C++, Linux, FreeBSD, math] for work in Warsaw, Poland ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: [Haskell-cafe] Project postmortem
On 02 December 2005 12:49, Tomasz Zielonka wrote: On Fri, Dec 02, 2005 at 12:39:25PM -, Simon Marlow wrote: Do I understand correctly that another workaround is - don't compile your programs with -threaded ? No, the bug isn't related to -threaded. It still occurs without -threaded. Let's check that now I understand - so the sequence call gethostbyname read the returned hostent is written in Haskell, and many such sequences can be interleaved when using Concurrent Haskell? Yes, exactly. Cheers, Simon ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: [Haskell-cafe] Project postmortem
On 02 December 2005 12:25, Joel Reymont wrote: I thought that if -threaded is not used then all the blocking IO is assigned a separate OS thread. No - the runtime is completely single-threaded without -threaded. Blocking I/O is managed by the runtime. With -threaded, blocking I/O is managed by a Haskell thread. The programmer shouldn't see any difference in the behaviour of I/O. Is the documentation for -threaded lacking? I realise it's a bit terse, but do you have any concrete suggestions for improving it? Cheers, Simon ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
