From dc99f950baf109a139ea89181e53f3b841f39142 Mon Sep 17 00:00:00 2001 From: Felipe Gasper Date: Mon, 24 Jun 2024 16:22:36 -0400 Subject: [PATCH 1/2] add performance note --- README.md | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/README.md b/README.md index c4fda247..f7151961 100644 --- a/README.md +++ b/README.md @@ -229,6 +229,12 @@ Any collection metadata mismatches will occur in a task with the type '`verifyCo In this case, '`failed_docs`' contains all the meta data mismatches, in this case an index named '`x_1`'. +# Performance + +- The migration-verifier optimizes for the case where a migration’s initial sync is completed **and** change events are relatively infrequent. If you start verification before initial sync finishes, or if the source cluster is too busy, the verification may freeze. + +The migration-verifier is also rather resource-hungry. To mitigate this, try limiting its number of workers (i.e., `--numWorkers`), its partition size (`--partitionSizeMB`), and/or its process group’s resource limits (see the `ulimit` command in POSIX OSes). + # Known Issues - The verifier may report missing documents on the destination that don’t actually appear to be missing (i.e., a nonexistent problem). This has been hard to reproduce. If missing documents are reported, it is good practice to check for false positives. From d2fadc92c2862f80c8bf7fad31dffbedc01be4d4 Mon Sep 17 00:00:00 2001 From: Felipe Gasper Date: Mon, 24 Jun 2024 16:23:31 -0400 Subject: [PATCH 2/2] remove bullet --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index f7151961..464988ac 100644 --- a/README.md +++ b/README.md @@ -231,7 +231,7 @@ In this case, '`failed_docs`' contains all the meta data mismatches, in this cas # Performance -- The migration-verifier optimizes for the case where a migration’s initial sync is completed **and** change events are relatively infrequent. If you start verification before initial sync finishes, or if the source cluster is too busy, the verification may freeze. +The migration-verifier optimizes for the case where a migration’s initial sync is completed **and** change events are relatively infrequent. If you start verification before initial sync finishes, or if the source cluster is too busy, the verification may freeze. The migration-verifier is also rather resource-hungry. To mitigate this, try limiting its number of workers (i.e., `--numWorkers`), its partition size (`--partitionSizeMB`), and/or its process group’s resource limits (see the `ulimit` command in POSIX OSes).