About omni.ja

The same below is also valid for 42.1.

I am running firefox under several user id:s at simultaneously.
I got the feeling that the different users could be hanged up by some other of the users. My feeling told me that this might depend on a poor designed java.
After having started to try to get to the problem I did find that some did “eat memory” until the whole computer freeze.
The responsible process for this was “web” in the ksysguard. A process using something in the omni.ja. Also very odd as I could see that other users could launch a pipe to “my” process. One at the time. Also it is always the same user that start this process. I also have a unverified feeling the a Flash is involved in some way. The only user that uses the Flash is the one that start this “web” process.

Is there any “safe” flash player? an dhow do I clean up from existing ones. The different (?) flash players comes with some TV web sites.

I have tried to run some other web browser but that is another story.

In a short answer, there is no such thing as a “safe” Flash player, and that might mean many things beyond what you described (eg the notorious Flash cookies which have been commonly abused by developers because they are nothing like ordinary cookies).

It’s why Apply decided to ban Flash from all Apple devices.
It’s why if you ever monitor your system resources when anything Flash launches, your system resources will quickly max out.

It’s just what Flash is, and the more you prevent any kind of Flash running, the better your machines will run.

As for Java…
It’s a YMMV thing. By default relatively few threads/resources are allocated to a JVM but that should OK for individual use.
It’s very well known that if you run a Java Server application that spawns a multitude of threads, you need to increase resources allocated to your JVMs. Beyond that, it can be a complex process optimizing Java.