How to tell who is connected ?

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Daisuke Yoshida

Aug 10, 2021, 7:43:45 PMAug 10
Hi guys,

I have a question for all of you. Is there a way to tell who is connected and who is disconnected from the hub server ? 

What I want to do is that from the hub server I want to find out who (public IP address) is connected to the hub server.

From the logs produced from the hub server I see the following message:

mThreadPool default maxThreadCount = 1
mThreadPool maxThreadCount previously set to 16
JackTrip HUB SERVER: UDP Base Port set to 61002
JackTrip HUB SERVER: Waiting for client connections...
JackTrip HUB SERVER: Hub auto audio patch setting = 0 (server-to-clients)
JackTimedDriver::Process XRun = 9 usec
JackTrip HUB SERVER: Client Connection Received!
JackTrip HUB SERVER: Client Connect Received from Address : ::ffff:
JackTrip HUB SERVER: Reading UDP port from Client...
JackTrip HUB SERVER: Client UDP Port is = 4464
JackTrip HUB SERVER: Sending Final UDP Port to Client: 61002
Writing port: 61002
JackTrip HUB SERVER: Client TCP Connection Closed!
JackTrip HUB SERVER: Starting JackTripWorker...
Cannot lock down 82280346 byte memory area (Cannot allocate memory)
Setting JACK Process Callback...
The Sampling Rate is: 48000
The Audio Buffer Size is: 256 samples
or: 1024 bytes
The Number of Channels is: 2
Using UDP Protocol
Using JitterBuffer strategy 1
Waiting for Connection From a Client...
UDP Socket Receiving in Port: 61002
Waiting for Peer...
Cannot use real-time scheduling (RR/5)(1: Operation not permitted)
JackClient::AcquireSelfRealTime error
JackTrip HUB SERVER: Total Running Threads: 1
spawning jacktripWorker so change patch
Received Connection from Peer! <== this tells the user is connected

After the user ( is disconnected I see

UDP waiting too long (more than 30ms) for 
UDP waiting too long (more than 30ms) for
UDP waiting too long (more than 30ms) for
<== Is this where user is disconnected ?

So from the log I can tell who is successfully connected but can't tell who is disconnected.

Is there a command that I don't know of that can find such information ? Basically I want a list of IP addresses who are connected to the hub server.

Thanks : ) 

Mike O'Connor

Aug 11, 2021, 7:08:01 PMAug 11
to Jacktrip-users
hi Daisuke

one messy way to do it would be to set up a process that used Jmess to query who's connected to the hub session, save its results in its normal XML format and then parse that file for IP addresses of connected folks. Jmess can be found here:

here's a screen shot of what i'm thinking would be the starting point. from here you could

- chew through the XML file
- build a list of unique IP addresses
- compare that list to a saved list

definitely not elegant. :-)


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Daisuke Yoshida

Aug 12, 2021, 9:43:35 AMAug 12
Hi Mike, (Hello again : ) )

Thank you!
I didn't know about JMESS; let me play with it.
Yeah it's not the cleanest way but it may work.
Another way I can think of is that if I can access the data stream at the server side I should be tell how much data is incoming/outgoing and given the buffer size and sampling frequency 
I should be able to calculate how many users are using the hub server. 


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