Jens Geyer created THRIFT-4190:
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             Summary: improve C# TThreadPoolServer defaults
                 Key: THRIFT-4190
                 URL: https://issues.apache.org/jira/browse/THRIFT-4190
             Project: Thrift
          Issue Type: Improvement
          Components: C# - Library
            Reporter: Jens Geyer
            Assignee: Jens Geyer


The TThreadPoolServer uses hardcoded values to specify min/max number of 
threads, if the caller does not specify them. This is rather unexpected in my 
opinion, since the global C# ThreadPool (which is used internally) comes with 
its own defaults for all 4 values - yes, 4, not 2: there are different settings 
for the number of threads on one hand and the number of asyn IO completion 
ports on the other, and they are not necessary identical numbers. For example, 
on my machine I get these numbers by default:


- min 4 threads and 4 I/O completion ports
- max 37267 threads and 1000 I/O completion ports


There are several *problems* with this approach:

# There is really no way to bypass the defaults of min 10/10 and max 100/100 
that are hard-coded into TThreadPoolServer and use the defaults provided by the 
NET framework instead, since we can only pass number which is then used for 
threads AND io ports. In my example, no matter what value I pass, 37267 or 
1000, it will be something other than the defaults.
# It is rather unexpected to have Thrift override the default settings of the 
global thread pool object if I don't even provide values by calling one of the 
simpler TThreadPoolServer  CTORs.
# I'm not sure where the defaults are come from. Both numbers look like wild 
guesswork to me. The defaults provided by the runtime make much more sense, as 
they automatically adapt to the machine's capabilities.


My *proposal* to solve it comes in two parts:

# Change  the CTOR in a way that interprets 0 or negative values as intention 
to stick with the NET default settings. I think that is the best way to handle 
it, as the current implementation would just throw in a very defined way, so we 
don't get any compatibility conflicts here that pass undetectedly.
# Additionally make the default values both 0 (or negative) to enforce the 
system's defaults. Since this will be a breaking change, as it changes the 
crrent default behaviour, I'd like to know the opinions of the community before 
I commit that part of the changes.


Further reference
- [SetMinThreads 
method|https://msdn.microsoft.com/en-us/library/system.threading.threadpool.setminthreads(v=vs.110).aspx]
- [SetMaxThreads 
method|https://msdn.microsoft.com/en-us/library/system.threading.threadpool.setmaxthreads(v=vs.110).aspx]





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