Error: Protocol 7 Error (Request Block & putDataBlockList) and multiple new connections afterwards

[doris75]

we had a user who started a gui session in the morning which made a connection to our uda server and then make a few requests
then pause and resume
when it resumes we could see on the client side the following uda error message
Error: Protocol 7 Error (Request Block & putDataBlockList)
On the server side nothing
[2025-12-11T11:32:02.502][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][iplotDataAccess.udaAccess-__fetch_data_x][INFO]could not retrieve data and Protocol 7 Error (Request Block & putDataBlockList)
[2025-12-11T11:32:02.502][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][iplotlib.interface.iplotSignalAdapter-set_da_fail][WARNING]Data Access Error: ErrCode: -1 | getData failed. Error: Protocol 7 Error (Request Block & putDataBlockList) for the signal: VAC-TKM-PPC-CP:MP0062-PTCP00-XI0
[2025-12-11T11:32:02.506][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:02.849][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:02.945][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.022][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.023][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][iplotDataAccess.udaAccess-__fetch_data_x][INFO]could not retrieve data and Protocol 7 Error (Request Block & putDataBlockList)
[2025-12-11T11:32:03.023][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][iplotlib.interface.iplotSignalAdapter-set_da_fail][WARNING]Data Access Error: ErrCode: -1 | getData failed. Error: Protocol 7 Error (Request Block & putDataBlockList) for the signal: VAC-TKM-PPC-CP-VI:MT0010-TTCP03-XI0
[2025-12-11T11:32:03.027][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.201][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.403][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.601][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.723][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][mint.models.mtSignalsModel-create_signals][WARNING]Ignored wrong stack value:
[2025-12-11T11:32:03.748][4501ws-cc-7220.codac.iter.org:ianneta][MainProcess:1471564][iplotDataAccess.udaAccess-__fetch_data_x][INFO]could not retrieve data and ERROR udaPlugin: Requested interval is empty

and since this error, each request is triggering a new connection until it reaches the limit... too many connections
the log on the server side
s=False) 0 -1 UDA UDA ] 9706 8504 [ERROR udaPlugin: Requested interval is empty] 14.051 9 9 [1471564 3254426] []
10.128.6.13 - ianna [Thu Dec 11 08:52:04 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MP0081-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754384445000000000,endTime=1754384605000000000,
extSamples=True) 0 -1 UDA UDA ] 0 11560 [] 34.878 9 9 [1471564 3254426] []
10.128.6.13 - ianna [Thu Dec 11 08:52:04 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CVB:MFT0111-FTCB00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754384445000000000,endTime=1754384605000000000,e
xtSamples=False) 0 -1 UDA UDA ] 0 20920 [] 38.201 9 9 [1471564 3254426] []
10.128.6.13 - ianna [Thu Dec 11 11:32:02 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP:MP0063-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,ext
Samples=True) 0 -1 UDA UDA ] 0 11976 [] 194.298 9 9 [1471564 3259023] []
10.128.6.13 - ianna [Thu Dec 11 11:32:02 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP:MP0072-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,ext
Samples=True) 0 -1 UDA UDA ] 0 11608 [] 84.372 9 9 [1471564 3259023] []
10.128.6.13 - ianna [Thu Dec 11 11:32:02 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP:MP0073-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,ext
Samples=True) 0 -1 UDA UDA ] 0 11864 [] 1071.13 9 9 [1471564 3259023] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MT0010-TTCP01-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 13704 [] 114.889 9 9 [1471564 3259033] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MT0011-TTCP04-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 13720 [] 114.611 9 9 [1471564 3259042] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MT0011-TTCP02-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 13720 [] 137.784 9 9 [1471564 3259051] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MP0033-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 12840 [] 114.917 9 9 [1471564 3259051] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-GIS-LAB-VIEW:Moles,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,extSample
s=False) 0 -1 UDA UDA ] 9706 8504 [ERROR udaPlugin: Requested interval is empty] 24.298 9 9 [1471564 3259051] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MP0032-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 11048 [] 118.376 9 9 [1471564 3259060] []
10.128.6.13 - ianna [Thu Dec 11 11:32:03 2025] [1000 getData(variable=/ITER/VAC-TKM-PPC-CP-VI:MP0081-PTCP00-XI0,tsFormat=absolute,decSamples=-1,startTime=1754580666000000000,endTime=1754580714000000000,
extSamples=True) 0 -1 UDA UDA ] 0 10728 [] 59.379 9 9 [1471564 3259060] []

[doris75]

to specify uda version 2.8.0 so maybe it is already solved in the last version of uda
[abadiel@io-ls-udasrv1 ~]$ ps -ef |grep uda
codac 3252312 1 0 07:40 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3252317 3252312 0 07:40 ? 00:00:24 /opt/codac-7.3/bin/uda_server
codac 3254001 1 0 08:36 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3254006 3254001 0 08:36 ? 00:00:21 /opt/codac-7.3/bin/uda_server
codac 3255719 1 0 09:33 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3255724 3255719 0 09:33 ? 00:00:14 /opt/codac-7.3/bin/uda_server
codac 3256591 1 0 10:05 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3256596 3256591 0 10:05 ? 00:00:12 /opt/codac-7.3/bin/uda_server
codac 3259018 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259023 3259018 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259028 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259033 3259028 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259037 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259042 3259037 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259046 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259051 3259046 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259055 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259060 3259055 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259064 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259069 3259064 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259073 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259078 3259073 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259082 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259087 3259082 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259091 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259096 3259091 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259100 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh
codac 3259105 3259100 0 11:32 ? 00:00:04 /opt/codac-7.3/bin/uda_server
codac 3259109 1 0 11:32 ? 00:00:00 /bin/bash /opt/codac-7.3/bin/udaserver.sh

[stephen-dixon]

This is strange behaviour we've not seen before. Our First thought is that the socket is becoming corrupted somehow and this isn't being handled properly. It seems like after the first failure the client continues to encounter this consistent error during the request block transfer protocol but never closes the socket connection. so the client creates a new server connection on each request but every server stays alive listening for their entire timeout lifetime (10 mins or longer). The expected behaviour is that the server process ends when the client cuts the connection. I've not seen accumulation of servers like this before.

Your versions do predate the fixes you made to the thread-safety of the error handling so maybe it will be fixed by that, though i can't be certain.

Without a reproducible example it's hard for us to diagnose further as we'd really need to run this case through a debugger to understand the state.

I guess the short-term work-around is to stop and restart the client process when this situation occurs, I'm sorry we can't really say more. Let us know if this is a recurrent problem and not just a one-off and if it's consistently triggered by the pause and restart usage pattern.