I have a java application and it connects to multiple LibreOffice Applications over TCP socket. The Application may be busy or not. How can i be sure abut it?
Is there any way to check if the desired Libreoffice Application is available or not?
There is only one application soffice(.exe).
You can’t. Even, if you ask, this may change anytime. So you can only try to connect and have to check, if this was successful.
PS: please change your tag “base” to something like “java” or “tcp socket”, as “base” is the name of the LO-component connecting to databases.
soffice.bin rather; because soffice.exe is just a bootstrap launcher (on Windows), and may even not run at all in some cases.
You need to provide details about the actual problem you are facing. Because the obvious answer would be: you attempt to connect over the provided TCP socket, and if it is successful, it is the test that shows that it is availavle. But you wouldn’t ask this question, if there wasn’t another problem, right? 
Possibly your question is about availability of the installed modules, that are available on the other side of the connection (and then the “busy” bit is a mistake)? There’s no negotiation of this information, AFAICT.
The LibreOffice has a thread limit. It accepts multiple request but at some point i may got error , if i try to work with multiple process at the same LibreOffice App.
I would like to check, if the LibreOffice Application can handle one one more process or not