SERVER-34844 Relax timing requirements in apply_batches_totalMillis.js

(cherry picked from commit 604e8e63813f090b7565f0a1094f7bb63dae57fc)

1 files changed, 10 insertions, 9 deletions

diff --git a/jstests/replsets/apply_batches_totalMillis.js b/jstests/replsets/apply_batches_totalMillis.js
index fd8b2872065..7808eb4c869 100644
--- a/jstests/replsets/apply_batches_totalMillis.js
+++ b/jstests/replsets/apply_batches_totalMillis.js
@@ -1,7 +1,9 @@
 /**
  * serverStatus.metrics.repl.apply.batches.totalMillis is a cumulative measure of how much time a
  * node spends applying batches. This test checks that it includes the time spent waiting for
- * batches to finish, by comparing the time recorded after replicating a small and a large load.
+ * batches to finish by making sure that the timer is cumulative and monotonic. We cannot make
+ * any assumptions about how long batches actually take as that can vary enormously between
+ * machines and test runs.
  */
 
 (function() {
@@ -37,26 +39,25 @@ let coll = primary.getDB(name)["foo"];
 // Perform an initial write on the system and ensure steady state.
 assert.writeOK(coll.insert({init: 0}));
 rst.awaitReplication();
+
 let baseTime = getTotalMillis(secondary);
+jsTestLog(`Base time recorded: ${baseTime}ms`);
 
 // Introduce a small load and wait for it to be replicated.
 performBulkInsert(coll, "small", 1000);
 
-// Record the time spent applying the small load.
+// Record the time spent applying the small load. The timer should not move backwards.
 let timeAfterSmall = getTotalMillis(secondary);
-let deltaSmall = timeAfterSmall - baseTime;
+jsTestLog(`Time recorded after smaller batch: ${timeAfterSmall}ms`);
+assert.gte(timeAfterSmall, baseTime);
 
 // Insert a significantly larger load.
 performBulkInsert(coll, "large", 20000);
 
 // Record the time spent applying the large load.
 let timeAfterLarge = getTotalMillis(secondary);
-let deltaLarge = timeAfterLarge - timeAfterSmall;
-
-jsTestLog(`Recorded deltas: {small: ${deltaSmall}ms, large: ${deltaLarge}ms}.`);
+jsTestLog(`Time recorded after larger batch: ${timeAfterLarge}ms`);
+assert.gte(timeAfterLarge, timeAfterSmall);
 
-// We should have recorded at least as much time on the second load as we did on the first.
-// This is a crude comparison that is only taken to check that the timer is used correctly.
-assert(deltaLarge >= deltaSmall, "Expected a higher net totalMillis for the larger load.");
 rst.stopSet();
 })();
\ No newline at end of file