During heavy bulk  operations, the Neo4j server sometimes throws the following exception:

Caused by: java.lang.RuntimeException: java.util.concurrent.ExecutionException: org.neo4j.internal.unsafe.NativeMemoryAllocationRefusedError: Failed to allocate 2097152 bytes. So far 197242580263 bytes have already been successfully allocated. The system currently has 540275736576 bytes total physical memory, 289180123136 bytes committed virtual memory, and 66026917888 bytes free physical memory. Relevant system properties: "java.vm.name" = "OpenJDK 64-Bit Server VM", "java.vm.vendor" = "Red Hat, Inc.", "os.arch" = "amd64".
at org.neo4j.index.internal.gbptree.CrashGenerationCleaner.awaitAll(CrashGenerationCleaner.java:261)
at org.neo4j.index.internal.gbptree.CrashGenerationCleaner.clean(CrashGenerationCleaner.java:116)
at org.neo4j.index.internal.gbptree.GBPTreeCleanupJob.run(GBPTreeCleanupJob.java:74)
at org.neo4j.index.internal.gbptree.GroupingRecoveryCleanupWorkCollector.lambda$allJobs$0(GroupingRecoveryCleanupWorkCollector.java:104)
at org.neo4j.kernel.impl.scheduler.ThreadPool.lambda$asCallable$1(ThreadPool.java:140)
at org.neo4j.kernel.impl.scheduler.ThreadPool.lambda$submit$0(ThreadPool.java:112)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at java.base/java.lang.Thread.run(Thread.java:1583)

Root Cause

Linux (Red Hat / CentOS) uses the over‑commit mechanism to determine whether a process can request more virtual memory than is physically available.
When the kernel’s vm.overcommit_memory setting is 0 (heuristic) or 2 (always deny), large or numerous concurrent memory requests can fail even if the system still has free RAM.

Neo4j’s delete cleanup jobs require several megabytes of native memory at a time; with the default over‑commit policy, the kernel may deny those requests.

Solution

Work with the IT administrator to change the OS's   vm.overcommit_memory  to 1 

Ref : https://www.kernel.org/doc/Documentation/vm/overcommit-accounting