SERVER-38015 Test many concurrent transactions

Author: GeertBosch

jstests/core/txns/many_txns.js

@@ -0,0 +1,91 @@
+// SERVER-38015 Test having many interactive transactions to ensure we don't hold on to too
+// many resources (like "write tickets") and don't prevent other operations from succeeding.
+// @tags: [uses_transactions]
+(function() {
+    "use strict";
+
+    const dbName = "test";
+    const collName = "many_txns";
+    const numTxns = 150;
+
+    const testDB = db.getSiblingDB(dbName);
+    const coll = testDB[collName];
+
+    testDB.runCommand({drop: collName, writeConcern: {w: "majority"}});
+    assert.commandWorked(
+        testDB.runCommand({create: coll.getName(), writeConcern: {w: "majority"}}));
+
+    const sessionOptions = {causalConsistency: false};
+
+    const startTime = new Date();
+
+    // Non-transactional write to give something to find.
+    const initialDoc = {_id: "pretransaction1", x: 0};
+    assert.commandWorked(coll.insert(initialDoc, {writeConcern: {w: "majority"}}));
+
+    // Start many transactions, each inserting two documents.
+    jsTest.log("Start " + numTxns + " transactions, each inserting two documents");
+    var sessions = [];
+    for (let txnNr = 0; txnNr < numTxns; ++txnNr) {
+        const session = testDB.getMongo().startSession(sessionOptions);
+        sessions[txnNr] = session;
+        const sessionDb = session.getDatabase(dbName);
+        const sessionColl = sessionDb[collName];
+        let doc = seq => ({_id: "txn-" + txnNr + "-" + seq});
+
+        session.startTransaction();
+
+        let docs = sessionColl.find({}).toArray();
+        assert.sameMembers(docs, [initialDoc]);
+
+        // Insert a doc within the transaction.
+        assert.commandWorked(sessionColl.insert(doc(1)));
+
+        // Read in the same transaction returns the doc, but not from other txns.
+        docs = sessionColl.find({_id: {$ne: initialDoc._id}}).toArray();
+        assert.sameMembers(docs, [doc(1)]);
+
+        // Insert a doc within a transaction.
+        assert.commandWorked(sessionColl.insert(doc(2)));
+    }
+    const secondDoc = {_id: "midtransactions", x: 1};
+    assert.commandWorked(coll.insert(secondDoc, {writeConcern: {w: "majority"}}));
+
+    // Commit all sessions.
+    jsTest.log("Commit all transactions.");
+    let numAborted = 0;
+    for (let txnNr = 0; txnNr < numTxns; ++txnNr) {
+        // First check that a non-transactional operation conflicts and times out quickly.
+        let doc = seq => ({_id: "txn-" + txnNr + "-" + seq});
+        let insertCmd = {insert: collName, documents: [doc(1)], maxTimeMS: 10};
+        let insertRes = testDB.runCommand(insertCmd);
+
+        const session = sessions[txnNr];
+        let commitRes = session.commitTransaction_forTesting();
+        if (commitRes.code === ErrorCodes.NoSuchTransaction) {
+            ++numAborted;
+            continue;
+        }
+        assert.commandWorked(commitRes, "couldn't commit transaction " + txnNr);
+        assert.commandFailedWithCode(insertRes, ErrorCodes.MaxTimeMSExpired, tojson({insertCmd}));
+
+        // Read with default read concern sees the committed transaction.
+        assert.eq(doc(1), coll.findOne(doc(1)));
+        assert.eq(doc(2), coll.findOne(doc(2)));
+        session.endSession();
+    }
+
+    assert.eq(initialDoc, coll.findOne(initialDoc));
+    assert.eq(secondDoc, coll.findOne(secondDoc));
+
+    const elapsedTime = new Date() - startTime;
+    jsTest.log("Test completed with " + numAborted + " aborted transactions in " + elapsedTime +
+               " ms");
+
+    // Check whether we should expect aborts. If the parameter doesn't exist (mongos) don't check.
+    const getParamRes = db.adminCommand({getParameter: 1, transactionLifetimeLimitSeconds: 1});
+    if (getParamRes.ok && elapsedTime < getParamRes.transactionLifetimeLimitSeconds)
+        assert.eq(numAborted,
+                  0,
+                  "should not get aborts when transactionLifetimeLimitSeconds not exceeded");
+}());