PyKX with Prefect

Community Support
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1

https://learninghub.kx.com/forums/topic/pykx-with-prefect

Hi There,

We’re trying to integrate our KDB Processes with Prefect by running PyKX via an IPC port. We are running flows/tasks via Prefect that contain PyKX libraries to establish a connection. A snippet of the code can be found below:

import os 
import time 
import subprocess 
from prefect import flow, task, get_run_logger 
from prefect_shell import ShellOperation 
import pykx as kx 
def setup(): 
     token = subprocess.Popen('\\ccl\data\extlib\KDBSecToken.exe', stdout=subprocess.PIPE).communicate()[0].decode('utf-8') 
     masterConn = kx.SyncQConnection( host='v-kdbr-01', port=5000, username='cleung', password=token, timeout=3.0 ) 
     user = masterConn('.z.u') 
     print('User = ' + user.py()) 
     port = masterConn('getProcessClient[`prefect_testing_base;`pykx_test]') 
     print('Port = ' + str(port.py())) 
     masterConn.close() 
     global conn 
     conn = kx.SyncQConnection( host='v-kdbr-01', port=port.py(), username='cleung', password=token) 
     user = conn('.z.u') 
     print('User = ' + user.py()) 

@flow() 
def ibes_pykx():
     setup() logger = get_run_logger() 
     logger.info("Initializing initial arguments") 
     dailyDates = conn('dailyDates: .dt.drb[.dt.shiftdateb[exec max date from QModelD;-3]; exec max date from QModelD];') 
     logFile = conn('inLogFile:`') 
     updateIBESTickers_result = updateIBESTickers.submit() 
     saveRecRevAI260_result = saveRecRevAI260.submit(wait_for=[updateIBESTickers_result])

This works fine when running it on the console (on Visual Studio Code). However, when it comes time to deploy, we keep getting this issue. A deployment on prefect essentially builds the function so it can be used on the Prefect UI.

Script at ‘./Script/ibes_pykx.py’ encountered an exception: ValueError(‘signal only works in main thread’)

Were not sure what to do as it seems like an OS level issue. So far, I am confident that it is the

import pykx as kx

line that is messing it up. However, Im unsure as to what the best approach is to solve this.

Thanks so much for the help, I know it’s a pretty niche area and any advice would be GREATLY appreciated

2

We added some functionality in version 2.3.0

https://code.kx.com/pykx/2.4/release-notes/changelog.html#pykx-230

If you enable beta features as well as pykx threading all calls into q from any python thread will be run as if they were calling from the main thread which allows python multithreaded programs to use IPC connections in licensed mode.

You can enable this functionality like this:

import os
os.environ['PYKX_THREADING'] = '1'
os.environ['PYKX_BETA_FEATURES'] = '1'
import pykx as kx

You will also want to ensure that kx.shutdown_thread()​ is called when the script finishes. The safest way to do this is within a try​ – finally​ block like this.

if __name__ == '__main__':
    try:
        main()
    finally:
        kx.shutdown_thread()

More information about this functionality and an example can be found within our documentation:

https://code.kx.com/pykx/2.4/examples/threaded_execution/threading.html