There's also a StackOverflowError thrown. Unclear if that's the cause, or an effect of the timeout.

...
[2019-06-25T15:23:34.926285Z] Gathering output for process 30953
[ELAPSED: 3983 ms]
[logging stdout to PrintSharedArchiveAndExit-0000-dump.stdout]
[logging stderr to PrintSharedArchiveAndExit-0000-dump.stderr]
[STDERR]

[2019-06-25T15:23:37.380166Z] Waiting for completion for process 30953
Timeout refired 36000 times
----------System.err:(14/1203)----------
Exception in thread "process reaper" java.lang.StackOverflowError
	at java.base/java.util.concurrent.ConcurrentHashMap.fullAddCount(ConcurrentHashMap.java:2576)
	at java.base/java.util.concurrent.ConcurrentHashMap.addCount(ConcurrentHashMap.java:2326)
	at java.base/java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1075)
	at java.base/java.util.concurrent.ConcurrentHashMap.putIfAbsent(ConcurrentHashMap.java:1541)
	at java.base/java.lang.invoke.MethodType$ConcurrentWeakInternSet.add(MethodType.java:1380)
	at java.base/java.lang.invoke.MethodType.makeImpl(MethodType.java:327)
	at java.base/java.lang.invoke.MethodHandleNatives.findMethodHandleType(MethodHandleNatives.java:377)
	at java.base/java.util.concurrent.CompletableFuture.completeValue(CompletableFuture.java:305)
	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2143)
	at java.base/java.lang.ProcessHandleImpl$1.run(ProcessHandleImpl.java:162)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:830)