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danic opened this issue Mar 9, 2016 · 8 comments
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Exception in flask and mod_wsgi app #180

danic opened this issue Mar 9, 2016 · 8 comments

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@danic
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danic commented Mar 9, 2016

Has anybody managed to successfully run a (non-trivial) Flask app under Apache mod_wsgi using pythonnet ? My app keeps throwing this exception:

"System.TypeInitializationException: The type initializer for 'System.Web.Script.Serialization.JavaScriptSerializer' threw an exception. ---> System.Configuration.ConfigurationErrorsException: Error Initializing the configuration system. ---> System.ArgumentException: The 'ExeConfigFilename' argument cannot be null"

as soon as it tries to use a clr object that deserializes some JSON. Full details here:

http://stackoverflow.com/questions/35872504/pythonnet-exception-the-execonfigfilename-argument-cannot-be-null

On this bug Mono added the mono_domain_set_config API to help with this situation. I don't see that method being called in the Mono code. Neither it seems to be called if I run the code in this other bug through gdb. However the code does not crash, as on the other hand I would expect as my version of Mono does have that bugfix. Still don't quite understand how that bug fix works though if it's not being called. Obviously missing something fairly fundamental here.
Maybe pythonnet PyNet_Init needs to explicitly call mono_domain_set_config ?
@danic
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danic commented Mar 9, 2016

It does indeed seem that adding a call to mono_domain_set_config in PyNet_Init fixes the issue:

diff --git a/src/monoclr/pynetinit.c b/src/monoclr/pynetinit.c
index eaa1d9c..ed247f2 100644
--- a/src/monoclr/pynetinit.c
+++ b/src/monoclr/pynetinit.c
@@ -31,6 +31,7 @@ PyNet_Args* PyNet_Init(int ext) {
     pn_args->shutdown_name = "Python.Runtime:Shutdown()";

     pn_args->domain = mono_jit_init_version(MONO_DOMAIN, MONO_VERSION);
+    mono_domain_set_config(pn_args->domain, ".", "Python.Runtime.dll.config");

danic pushed a commit to danic/pythonnet that referenced this issue Mar 9, 2016
Fix for pythonnet#180
dd5d2b6
@danic
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danic commented Mar 9, 2016

See #181. Travis build failing because it's using an ancient Mono 3.2.8 which does not even have the mono_domain_set_config fix (that was rolled out in 3.8.0). I'm on 4.2.2.

@den-run-ai
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@danic see this doc how to update mono on travis ci:

https://docs.travis-ci.com/user/languages/csharp/

@danic
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danic commented Mar 10, 2016

@denfromufa saw that thanks. Did try a couple of things on my fork by specifying mono versions but it doesn't work because Travis is using ancient Precise VMs. I did try the new Trusty image but the build hung out and failed. It's kind of irrelevant though as I know my fix works on both distros in fact as I have both a Precise box and a Trusty AWS instance both with Mono 4.2.2. So I'll leave it at that for the time being.

@den-run-ai
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@danic maybe it is possible to download latest mono binaries (4.2.2) instead of compiling on build machine? it probably time outs before it builds due to constrained resources.

@danic
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danic commented Mar 11, 2016

After a few disagreements with Travis I finally managed to persuade it to build it. It works now.

danic pushed a commit to danic/pythonnet that referenced this issue Mar 14, 2016
Fix for pythonnet#180
7e82363
danic pushed a commit to danic/pythonnet that referenced this issue Mar 14, 2016
Fix for pythonnet#180
7bccf74
@mikofski mikofski mentioned this issue Mar 15, 2016
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tonyroberts added a commit that referenced this issue Mar 15, 2016
@tonyroberts
Merge pull request #181 from danic/master
950bdea 
Fix for #180
tonyroberts added a commit that referenced this issue Mar 15, 2016
@tonyroberts
Revert "Fix for #180"
048caf3
tonyroberts added a commit that referenced this issue Mar 15, 2016
@tonyroberts
Merge pull request #188 from pythonnet/revert-181-master
3510dd8 
Revert "Fix for #180"
@tonyroberts tonyroberts reopened this Mar 15, 2016
@tonyroberts
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I've re-opened this as the PR was against the wrong branch. Please submit a new PR against the develop branch.

tonyroberts pushed a commit to tonyroberts/pythonnet that referenced this issue Mar 15, 2016
@tonyroberts
Fix for pythonnet#180
9069397
tonyroberts pushed a commit to tonyroberts/pythonnet that referenced this issue Mar 15, 2016
@tonyroberts
Fix for pythonnet#180
3ec1f30 
Update travis CI build to use latest mono and add a call to
mono_domain_set_config to solve problems using pythonnet with
mod_wsgi.
tonyroberts pushed a commit to tonyroberts/pythonnet that referenced this issue Mar 15, 2016
@tonyroberts
Fix for pythonnet#180
37a4ea5 
Update travis CI build to use latest mono and add a call to mono_domain_set_config to solve problems using pythonnet with mod_wsgi.
@tonyroberts
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Done - see PR #189

tonyroberts added a commit that referenced this issue Mar 15, 2016
@tonyroberts
Merge pull request #189 from tonyroberts/develop
f94937e 
Fix for #180
@den-run-ai den-run-ai mentioned this issue Mar 20, 2017
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@danic @tonyroberts @den-run-ai