When Jenkins enters safe mode, if the executor is not shut down, the backup cannot be started, and the safe mode cannot be canceled, and Jenkins cannot run normally.

I gave the solution：When entering safe mode, force shutdown of running executors，

This will start the backup normally。In "\src\main\java\org\jvnet\hudson\plugins\thinbackup\utils\Utils.java"

 if (!jenkins.isQuietingDown() && starttime + unit.toMillis(timeout) < System.currentTimeMillis()) {
LOGGER.info("Force quiet mode for jenkins now and wait until all executors are idle.");
jenkins.doQuietDown();
//below is added by wangruxun
for (final Computer computer : computers) {
if (computer.countBusy() != 0)

}
}
} while (running);
}