This test calls into findDocIdWithSeparateWriterId with nWriters set to the max number of threads on the replication worker pool. This value is set here, and determined here. This value can be small when the replWriterThreadCount parameter is set to a low value or if the machine we are running the test on has a low number of available cores.

We can follow the precedent set by the other caller of this function, this test, which hard codes the number of writers to a larger value to decrease the likelihood of a hash collision.