Jenkins Executors dead - Jenkins LTS 1.625.2

[Stefan Herrmann]

We habe recently updated to the LTS 1.625.2. Under normal conditions it works fine. But whenn there are a couple of job triggered via SVN change executors start to hand. The show that the job is still runing. But as soon as i go to the jobs status page the job is already finished. As a consequence the executor is blocked for several minutes until jenkins detects the dead executor (DEAD is displayed in executor slot). Meanwhile the build queue fills up and processor load on the master increases drastically.
We upgraded from 1.5x. Since the job configuration has changed a downgrade is not trivial. Espeacially because this is a productive system with a couple of thousand jobs.
Jira Issue: JENKINS-31536
Are there any ideas on how to fix this problem.