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<== Date ==> <== Thread ==>
Subject: Re: memory leak after unloading of ca.lib
From: Xiaoqiang Wang <[email protected]>
To: Epics <[email protected]>
Date: Wed, 29 Mar 2017 21:33:48 +0200 
Hi,

Just for reference’s sake, I have wrongly attributed the hangup to unload ca.dll/Com.dll.
In my case, the hangup comes from a bug in Python cffi library and gets fixed.[1]

Best
Xiaoqiang

[1] https://bitbucket.org/cffi/cffi/commits/9fe2a9e060945f60c32a22d41d70c5a026fb146d

> On 23 Mar 2017, at 21:38, Wang Xiaoqiang (PSI) <[email protected]> wrote:
> 
> 
> Hi Carsten, Michael,
> 
> Sorry to revive this old thread. But I am facing similar problem to solve. This time not with Labview but with Python cffi.
> 
> From the discussion I understood that the workaround is not to unload libca/libCom.
> On Linux, I have used the RTLD_NODELETE flag and that solve the problem.(https://linux.die.net/man/3/dlopen)
> 
> On 64bit Windows, I made a boring wrapper dll. https://github.com/CaChannel/caffi/tree/master/wrapper
> The wrapper loads ca.dll with LoadLibrary call and calls the loaded symbols for the CA API. And at the end it does not call FreeLibrary, so that the loaded symbols live until the program ends. Do you guys see any problem with this approach?
> 
> 
> Best
> Xiaoqiang
> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Carsten Winkler
> Sent: Donnerstag, 23. Februar 2017 09:50
> To: [email protected]
> Subject: memory leak after unloading of ca.lib
> 
> Hi there,
> 
> when your project (e.g. LabVIEW) uses dynamic loading and unloading of channel access classes your main class will sometimes (at 64 bit nearly
> always) crush with a segmentation fault. The reason seems to be missing
> free() and delete functions in EPICS Base 3.14.12.6 (I'm sure this applies also to other EPICS Base versions).
> 
> I wrote a tiny test case to check it and it would be great to get any advise to solve the issue.
> 
> Best regards
> Carsten
> 
> 
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> 
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> 
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> 
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> 
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References:
memory leak after unloading of ca.lib Carsten Winkler
RE: memory leak after unloading of ca.lib Wang Xiaoqiang (PSI)
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