Re: [Pytables-users] concurrent accesses

2012-11-02 Thread Francesc Alted
On 11/2/12 5:19 PM, Ben Elliston wrote: > On Fri, Nov 02, 2012 at 04:56:55PM -0400, Francesc Alted wrote: > >> Hmm, that's strange. Using lzo or zlib works for you? > Well, it seems that switching compression algorithms could be a > nightmare (or can I do this with ptrepack?). Yes, ptrepack can d

Re: [Pytables-users] concurrent accesses

2012-11-02 Thread Ben Elliston
On Fri, Nov 02, 2012 at 04:56:55PM -0400, Francesc Alted wrote: > Hmm, that's strange. Using lzo or zlib works for you? Well, it seems that switching compression algorithms could be a nightmare (or can I do this with ptrepack?). However, I may have a workaround: I now open the HDF5 file with ta

Re: [Pytables-users] concurrent accesses

2012-11-02 Thread Francesc Alted
On 11/2/12 4:49 PM, Ben Elliston wrote: > Hi Francesc > >> Hmm, now that I think, Blosc is not thread safe, and that can bring >> these sort of problems if you use it from several threads (but it >> should be safe when using several *processes*). > I am using multiprocessing.Pool, like so: > > if _

Re: [Pytables-users] concurrent accesses

2012-11-02 Thread Ben Elliston
Hi Francesc > Hmm, now that I think, Blosc is not thread safe, and that can bring > these sort of problems if you use it from several threads (but it > should be safe when using several *processes*). I am using multiprocessing.Pool, like so: if __name__ == '__main__': pool = Pool(processes=2)

Re: [Pytables-users] concurrent accesses

2012-11-02 Thread Francesc Alted
On 11/2/12 4:22 PM, Ben Elliston wrote: > My reading of the PyTables FAQ is that concurrent read access should > be safe with PyTables. However, when using a pool of worker processes > to read different parts of a large blosc-compressed CArray, I see: > > HDF5-DIAG: Error detected in HDF5 (1.8.8) t

[Pytables-users] concurrent accesses

2012-11-02 Thread Ben Elliston
My reading of the PyTables FAQ is that concurrent read access should be safe with PyTables. However, when using a pool of worker processes to read different parts of a large blosc-compressed CArray, I see: HDF5-DIAG: Error detected in HDF5 (1.8.8) thread 140476163647232: #000: ../../../src/H5Dio