[lttng-dev] Any tips to retrieve the relationship between socket-related processes

[杨海]

Hello,


I read this article and want to know whether it is true that UDP cannot be synchronized between traces and experimental branch is needed to get the below-mentioned issue resolved.
http://archive.eclipse.org/tracecompass/doc/org.eclipse.tracecompass.doc.user/Trace-synchronization.html#Trace_synchronization 


Regards
Hai
 
 
------------------ Original ------------------
From:  "杨海"<hai.yang at magic-shield.com>;
Date:  Thu, Jan 16, 2020 02:21 PM
To:  "lttng-dev"<lttng-dev at lists.lttng.org>; 

Subject:  Any tips to retrieve the relationship between socket-related processes

 

Hello,


Below briefly describe our question, hope to know how it can be supported by Lttng, babeltrace, analyses etc.


## IPC Trace：
### What we are doing:
We are trying to use lttng to find some IPC trace


### How we did:
Open Lttng first，then ran server(pid = 1812) and client(pid = 1819) and collect trace.
Client would send message to server and server would just echo what it received from client. They talk with each other by file "/tmp/python_unix_sockets_example". 
Scripts can be found here: https://github.com/Aaron0813/LinuxAPTLog/tree/master/socket_AF_UNIX
Trace Link: https://github.com/Aaron0813/LinuxAPTLog/tree/master/socket_AF_UNIX/with_pid_03


###  Trace Analysis(Lttng-analysis IO)
1. sshd transmit data：Since we were using ssh to connect server and client, that's why we can see this trace
2. 1819 client: read data from tty
3. 1819 client: send data by socket
4. 1819 client: send data by tty and ssh
5. 1812 server: send data to tty
6. 1812 server: receive data from client
7. Gsd-color gnome: do some display
8. A new round cycle starts after blue line




### Conclusion
In Lttng-Analysis' log：
1. Could not find any trace that related to /tmp/python_unix_sockets_example(we are using this file to communicate)
2. Could not find any relationship that can help us determine whether several processes are communicating


As for babeltrace log，we can only locate and understand the communication processes between server and client with the help of "/tmp/python_unix_sockets_example". However, we cannot find anything that can let us know that these two processes are communicating.


Regards
Hai
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