Parallel execution

Community Support
1

  Hello all,

  I am wondering if Multithreaded Input Mode option is designed to allow the parallel execution of different requests.  I start a long-running request, and would like to submit short-running requests in parallel, however after the long-running request starts, I am not able to submit to the server any other requests in parallel.  My function calls are implemented in a loaded C library.

  Thanks

2

You should be able to open second connection from different thread and send request in parallel. Don’t forget to clean up ( r0 all k created and received in the thread and call m9() )  before thread end, otherwise tls will leak

Cheers,
Oleg

3

new connections are accepted by the main thread,
which runs when no other threads are currently executing a query.

So in this mode, open your connections early, and re-use them.

4

So in other words, the query execution is still single-threaded even for select only queries?  The doc http://code.kx.com/wiki/Cookbook/MultithreadedInputMode seems to indicate the select queries can be run concurrently, and it’s up to the users to ensure there is no mutation. 

5

no. In this mode queries run concurrently, each in their own thread.
It is the accepting of new connections that requires currently executing queries to complete first. You can re-use a connection run another query.

These queries cannot change global data - it will throw an error to that thread if it tries.

The main thread can change globals. There’s a MWSR lock so all queries can run in read mode, but for the main thread to run, it must obtain the write lock.