Is there a limit to the number of times BBG will allow you to connect before it refuses the connection?

[tmiller198]

Code Sample, a copy-pastable example if possible

from owscipy.context import DbContext
from owscipy.util import load_config
import pandas as pd
from blp import blp
import logging

def main():
	#set connection profile
	context = DbContext()

	#get bond list
	def get_bond_data():
		df = context.frame("""SELECT TOP 3000 (YEAR([date]) * 10000 + MONTH([date]) * 100 + DAY([date])) AS 'bbg_date',
	    isin + ' Corp' AS 'bond_lookup',
	    (bidprice + offerprice) / 2 AS 'midprice'
        FROM bond_hist
        WHERE [date] >= '2021-07-01'
	    AND [date] < '2021-07-02'""","risk")
		return df
	
	#pull bond data
	df = get_bond_data()
	logging.info('bond data Downloaded') 

	#define BBG pull functions
	def get_dv01(a,b,c):
		bquery = blp.BlpQuery().start()
		try: df1 = bquery.bdp(a, ['YAS_RISK'],overrides=[('YAS_BOND_PX', float(b)),('USER_LOCAL_TRADE_DATE', int(c))])
		except ValueError:
			pass
		try:
			df1 = df1['YAS_RISK'].loc[df1.index[0]]
		finally: blp.BlpQuery().stop()
		return df1
 

	#get BBG data
	blp.BlpQuery().start()	
	df['dv01'] = df.apply(lambda row : get_dv01(row['bond_lookup'],row['midprice'], row['bbg_date']), axis = 1)
	blp.BlpQuery().stop()	    
	df['dv01'] = df['dv01'] * 100
	logging.info('DV01 Calculated')	

if __name__ == '__main__':
    main()

Problem description

I have a python script that pulls a bond ISIN, date, and prices in order to calculate the DV01 for the bond using BBG. The script runs fine when I only pull the top 100 rows, but if I increase to the top 3,000 rows for example, I get the below error:

2023-01-18 16:25:29 OWSCNYWKS105 root[39332] INFO bond data Downloaded

18JAN2023_16:27:08.808 39332:38476 WARN apicm_apiconnector.cpp:573 ApiConnector::negotiatorCallback localhost: Session negotiation failed for 127.0.0.1:8194 result = 1

18JAN2023_16:27:08.809 39332:38476 WARN blpapi_apicmadapter.cpp:336 blpapi.session.transporttcp.apicmadapter.{476} Failed BBCOMM session negotiation localhost:8194 <127.0.0.1:8194>

18JAN2023_16:27:08.809 39332:38476 WARN blpapi_platformtransporttcp.cpp:151 blpapi.session.transporttcp.{476}.localhost:8194 { platformId=0 } 127.0.0.1, session pool state=Failed

18JAN2023_16:27:08.810 39332:38476 WARN blpapi_platformcontroller.cpp:634 blpapi.session.platformcontroller.{476} Platform failed 1 consecutive connect attempts, stopped trying to reconnect. { PlatformId=0 }

18JAN2023_16:27:08.811 39332:6728 ERROR blpapi_sessionimpl.cpp:2445 blpapi.session.{476} Failed to start session: Failed to connect
2023-01-18 16:27:08 OWSCNYWKS105 blp.blp[39332] INFO Failed to connect to Bloomberg:
SessionStartupFailure = {
reason = {
source = "Session"
category = "IO_ERROR"
errorCode = 3
description = "Failed to connect"
}
}

Traceback (most recent call last):
File "s:\tmiller\Script\Python\test.py", line 45, in
main()
File "s:\tmiller\Script\Python\test.py", line 39, in main
df['dv01'] = df.apply(lambda row : get_dv01(row['bond_lookup'],row['midprice'], row['bbg_date']), axis = 1)
File "C:\Users\timmiller\Anaconda3\envs\singlesdash\lib\site-packages\pandas\core\frame.py", line 8740, in apply
return op.apply()
File "C:\Users\timmiller\Anaconda3\envs\singlesdash\lib\site-packages\pandas\core\apply.py", line 688, in apply
return self.apply_standard()
File "C:\Users\timmiller\Anaconda3\envs\singlesdash\lib\site-packages\pandas\core\apply.py", line 812, in apply_standard
results, res_index = self.apply_series_generator()
File "C:\Users\timmiller\Anaconda3\envs\singlesdash\lib\site-packages\pandas\core\apply.py", line 828, in apply_series_generator
results[i] = self.f(v)
File "s:\tmiller\Script\Python\test.py", line 39, in
df['dv01'] = df.apply(lambda row : get_dv01(row['bond_lookup'],row['midprice'], row['bbg_date']), axis = 1)
File "s:\tmiller\Script\Python\test.py", line 27, in get_dv01
bquery = blp.BlpQuery().start()
File "C:\Users\timmiller\Anaconda3\envs\singlesdash\lib\site-packages\blp\blp.py", line 546, in start
raise ConnectionError(f"Failed to start {self!r}")
ConnectionError: Failed to start <class 'blp.blp.BlpQuery'> with <address=localhost:8194><identity=None><eventHandler=None>

For reference owscipy is a self developed module to pull database data via SQL into a dataframe, of which frame is the function used to pull it and context is the connection profile. To make it replicable, I attached the exports of these dataframes. I'm not worried about the SQL part, as it works when there's only 100 entries.

Expected Output

top_100_examples.xlsx
top_3k_examples.xlsx

[matthewgilbert]

This looks like a Bloomberg specific question related to blpapi not the blp wrapper. I would contact Bloomberg help for this.

[gandhis1]

Only open the BLPQuery once, and make multiple bdp calls. The way you have it now, you are unnecessarily re-initializing it every single time.