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<== Date ==> <== Thread ==>

Subject: Re: Area Detector and high performance NVME devices
From: "Engbretson, Mark S." <engbretson@aps.anl.gov>
To: "Rivers, Mark L." <rivers@cars.uchicago.edu>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Fri, 30 Jun 2017 00:08:13 +0000
But wait . . . It can not work that way. Threads pop in and out of existence all the time. They may or may not use the HDF5 libraries, but if they do, they certainly would not want to have a dependency on code or constructs that could go "poof" at any instant.

What i want is an effect more like just opening 2 or more distinct files at once. If they are doing totally different things, with totally unrelated life cycles, what is the mutex protecting? 

On Jun 29, 2017, at 18:16, Mark Rivers <rivers@cars.uchicago.edu> wrote:

What you propose would not work, because the problem is not in NDFileHDF5.cpp, it is in the underlying HDF5 library.  There are global structures there that you would not be making multiple instances of, so they need to be protected by the mutex.

-----Original Message-----
From: Mark S. Engbretson [mailto:Engbretson@anl.gov] 
Sent: Thursday, June 29, 2017 5:05 PM
To: ulrik.pedersen@diamond.ac.uk; Mark Rivers
Cc: tech-talk@aps.anl.gov
Subject: RE: Area Detector and high performance NVME devices

For the sake of argument, what would happen if instead of creating multiple
instances of the HDF File plugin, which is actually the exact same entity, I
instead cloned the NDFileHDF5.cpp sources and made it a couple of unique
plugins named <NDFileHDF5>_A,B,C,and D. I can do this on windows system and
force every thread to have its own unique copy everything, so there is no
conflicts in non thread safe code just as you would not expect any mutex
issues from another process running on the system. 

I know that I should technically be able to use constructs such as  

void *handle1 = dlmopen(LM_ID_NEWLM, "/path/to/library.so", RTLD_NOW);
void *handle2 = dlmopen(LM_ID_NEWLM, "/path/to/library.so", RTLD_NOW);

Where the references is to the same shared library, but via difference
handles don't conflict.  But there should be easier ways to achieve the same
effect. I.e, with multiple file plugins, there are no common anythings that
should need that mutex lock or could be trashed.



-----Original Message-----
From: ulrik.pedersen@diamond.ac.uk [mailto:ulrik.pedersen@diamond.ac.uk] 
Sent: Thursday, June 29, 2017 9:34 AM
To: Engbretson@anl.gov; rivers@cars.uchicago.edu
Cc: tech-talk@aps.anl.gov
Subject: RE: Area Detector and high performance NVME devices

Replies:
RE: Area Detector and high performance NVME devices ulrik.pedersen
RE: Area Detector and high performance NVME devices Mark Rivers
References:
Area Detector and high performance NVME devices Mark S. Engbretson
RE: Area Detector and high performance NVME devices Mark Rivers
RE: Area Detector and high performance NVME devices Mark S. Engbretson
RE: Area Detector and high performance NVME devices Mark Rivers
RE: Area Detector and high performance NVME devices Mark S. Engbretson
Re: Area Detector and high performance NVME devices ulrik.pedersen
RE: Area Detector and high performance NVME devices Mark S. Engbretson
RE: Area Detector and high performance NVME devices ulrik.pedersen
RE: Area Detector and high performance NVME devices Mark Rivers
RE: Area Detector and high performance NVME devices Mark S. Engbretson
RE: Area Detector and high performance NVME devices ulrik.pedersen
RE: Area Detector and high performance NVME devices Mark S. Engbretson
RE: Area Detector and high performance NVME devices Mark Rivers

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