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/**
* Test ensures that exhausting the number of write tickets in the system does not prevent
* transactions from being reaped by the expired transaction reaper.
*
* @tags: [uses_transactions]
*/
(function() {
"use strict";
load("jstests/libs/parallelTester.js"); // for ScopedThread
// We set the number of write tickets to be a small value in order to avoid needing to spawn a
// large number of threads to exhaust all of the available ones.
const kNumWriteTickets = 5;
const rst = new ReplSetTest({
nodes: 1,
nodeOptions: {
setParameter: {
wiredTigerConcurrentWriteTransactions: kNumWriteTickets,
// Setting a transaction lifetime of 5 seconds works fine locally because the
// threads which attempt to run the drop command are spawned quickly enough. This
// might not be the case for Evergreen hosts and may need to be tuned accordingly.
transactionLifetimeLimitSeconds: 5,
}
}
});
rst.startSet();
rst.initiate();
const primary = rst.getPrimary();
const db = primary.getDB("test");
const session = primary.startSession({causalConsistency: false});
const sessionDb = session.getDatabase("test");
assert.commandWorked(db.runCommand({create: "mycoll"}));
session.startTransaction();
assert.commandWorked(sessionDb.mycoll.insert({}));
const threads = [];
for (let i = 0; i < kNumWriteTickets; ++i) {
const thread = new ScopedThread(function(host) {
try {
const conn = new Mongo(host);
const db = conn.getDB("test");
// Dropping a collection requires a database X lock and therefore blocks behind the
// transaction committing or aborting.
db.mycoll.drop();
return {ok: 1};
} catch (e) {
return {ok: 0, error: e.toString(), stack: e.stack};
}
}, primary.host);
threads.push(thread);
thread.start();
}
// We wait until all of the drop commands are waiting for a lock to know that we've exhausted
// all of the available write tickets.
assert.soon(
() => {
const ops = db.currentOp({"command.drop": "mycoll", waitingForLock: true});
return ops.inprog.length === kNumWriteTickets;
},
() => {
return `Didn't find ${kNumWriteTickets} drop commands running: ` +
tojson(db.currentOp());
});
// Attempting to perform another operation inside of the transaction will block and should
// eventually cause it to be aborted.
assert.commandFailedWithCode(sessionDb.mycoll.insert({}), ErrorCodes.LockTimeout);
for (let thread of threads) {
thread.join();
}
for (let thread of threads) {
assert.commandWorked(thread.returnData());
}
// Transaction should already be aborted.
assert.commandFailedWithCode(session.abortTransaction_forTesting(),
ErrorCodes.NoSuchTransaction);
session.endSession();
rst.stopSet();
})();
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