From c8ab2de5e1c1dea00aa7506efd19d4aabd92bf0f Mon Sep 17 00:00:00 2001
From: Jason Chan <jason.chan@mongodb.com>
Date: Wed, 27 Jan 2021 19:20:31 +0000
Subject: SERVER-53831 Force SpiderMonkey to garbage collect in
 ReplSetTest.checkOplogs

(cherry picked from commit 96fe72c36d370a4067240738f051021d4daf72ce)
---
 src/mongo/shell/replsettest.js | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'src')

diff --git a/src/mongo/shell/replsettest.js b/src/mongo/shell/replsettest.js
index 481c1f60339..1017d5072ce 100644
--- a/src/mongo/shell/replsettest.js
+++ b/src/mongo/shell/replsettest.js
@@ -2268,8 +2268,13 @@ var ReplSetTest = function(opts) {
             const firstReader = readers[firstReaderIndex];
             let prevOplogEntry;
             assert(firstReader.hasNext(), "oplog is empty while checkOplogs is called");
+            // Track the number of bytes we are reading as we check the oplog. We use this to avoid
+            // out-of-memory issues by calling to garbage collect whenever the memory footprint is
+            // large.
+            let bytesSinceGC = 0;
             while (firstReader.hasNext()) {
                 const oplogEntry = firstReader.next();
+                bytesSinceGC += Object.bsonsize(oplogEntry);
                 if (oplogEntry === kCappedPositionLostSentinel) {
                     // When using legacy OP_QUERY/OP_GET_MORE reads against mongos, it is
                     // possible for hasNext() to return true but for next() to throw an exception.
@@ -2284,6 +2289,7 @@ var ReplSetTest = function(opts) {
                     }
 
                     const otherOplogEntry = readers[i].next();
+                    bytesSinceGC += Object.bsonsize(otherOplogEntry);
                     if (otherOplogEntry && otherOplogEntry !== kCappedPositionLostSentinel) {
                         assertOplogEntriesEq.call(this,
                                                   oplogEntry,
@@ -2293,6 +2299,11 @@ var ReplSetTest = function(opts) {
                                                   prevOplogEntry);
                     }
                 }
+                // Garbage collect every 10MB.
+                if (bytesSinceGC > (10 * 1024 * 1024)) {
+                    gc();
+                    bytesSinceGC = 0;
+                }
                 prevOplogEntry = oplogEntry;
             }
         }
-- 
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