fix(adapter-mssql): acquire mutex in commit/rollback to prevent EREQINPROG error by MarkusLund · Pull Request #29119 · prisma/prisma

MarkusLund · 2026-02-02T15:13:47Z

Description

Fix race condition in MssqlTransaction where commit() or rollback() can be called while a query is still in progress, causing the mssql driver to throw EREQINPROG error.

Problem

The mssql driver throws EREQINPROG ("Can't rollback transaction. There is a request in progress.") when commit() or rollback() is invoked while a query is executing. This commonly occurs when a transaction times out during an in-flight query.

In the current implementation:

performIO() acquires a mutex before executing queries
commit() and rollback() do not acquire the mutex

This allows commit()/rollback() to race with active queries.

Solution

Modified commit() and rollback() to acquire the same mutex that performIO() uses. This ensures they wait for any active query to complete before executing.

Changes

packages/adapter-mssql/src/mssql.ts: Added mutex acquisition to commit() and rollback() methods
packages/adapter-mssql/src/mssql.test.ts: Added unit tests validating the mutex serialization behavior

Fixes #28994

Summary by CodeRabbit

Bug Fixes
- Commit and rollback now reliably wait for in‑flight queries using serialization, preventing race conditions and reducing unexpected transaction failures; improved handling of aborted (EABORT) and other error cases.
Tests
- Added comprehensive tests validating transaction serialization, concurrent query behavior, correct ordering of commit/rollback relative to running queries, and proper handling/rethrowing of abort and non-abort errors.

CLAassistant · 2026-02-02T15:13:57Z

All committers have signed the CLA.

coderabbitai · 2026-02-02T15:14:12Z

Walkthrough

Adds mutex-based serialization to MSSQL transaction commit and rollback, and a test suite that reproduces the pre-fix race and verifies serialization, ordering, and error handling (EABORT, non-EABORT, concurrent queries) with and without the mutex.

Changes

Cohort / File(s)	Summary
Transaction Mutex Implementation `packages/adapter-mssql/src/mssql.ts`	Wraps `commit()` and `rollback()` with mutex acquisition/release. `rollback()` preserves prior EABORT handling while executed under the lock; both methods release the mutex in finally blocks.
Mutex Serialization Test Suite `packages/adapter-mssql/src/mssql.test.ts`	Adds tests and mocks that reproduce the race when mutex is disabled (EREQINPROG), and verify that enabling the mutex serializes `queryRaw`, `commit`, and `rollback`, asserts event ordering, checks EABORT passthrough and non-EABORT rethrows, and tests concurrent queries followed by commit.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title 'fix(adapter-mssql): acquire mutex in commit/rollback to prevent EREQINPROG error' directly and clearly describes the main change: acquiring a mutex in commit/rollback methods to prevent the EREQINPROG error.
Linked Issues check	✅ Passed	The code changes directly address all key objectives from issue `#28994`: mutex acquisition prevents concurrent execution of commit/rollback with in-flight queries, thereby preventing the EREQINPROG error that made the adapter unusable.
Out of Scope Changes check	✅ Passed	All changes are scoped to the stated objective: modifications to mssql.ts implement mutex acquisition in commit/rollback, and test additions in mssql.test.ts verify the fix without introducing unrelated changes.

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Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@packages/adapter-mssql/src/mssql.test.ts`:
- Around line 173-182: Add a unit test that mirrors the rollback
error-propagation test but for commit: mockTransaction.commit should be mocked
to return a rejected Promise with an Error having message "Connection lost" and
code 'ECONNCLOSED', then call createTransaction(true) and assert that
tx.commit() rejects with that error message; reference mockTransaction.commit
and the commit method on the transaction created by createTransaction.

packages/adapter-mssql/src/mssql.test.ts

codspeed-hq · 2026-02-04T12:07:50Z

Merging this PR will improve performance by ×30

⚡ 1 improved benchmark
✅ 40 untouched benchmarks

Performance Changes

	Benchmark	`BASE`	`HEAD`	Efficiency
⚡	`compile findUnique simple`	26,137.5 µs	875.8 µs	×30

_{Comparing MarkusLund:fix/adapter-mssql-race-condition (70e179c) with main (36b57cb)}

jacek-prisma · 2026-02-05T15:58:19Z

Hi @MarkusLund, thanks for the pull request. Before we merge it though, could you sign the CLA?

packages/adapter-mssql/src/mssql.test.ts

jacek-prisma · 2026-02-05T16:04:47Z

The PR looks good, I think it can be merged when the CLA is signed and the one minor comment I left is addressed.

MarkusLund · 2026-02-05T20:01:01Z

CLA signed, @jacek-prisma 👍

jacek-prisma · 2026-02-06T10:24:53Z

packages/adapter-mssql/src/mssql.test.ts

+      },
+
+      async commit() {
+        if (useMutexForCommitRollback) {


useMutexForCommitRollback is now always true, so we can remove the parameter and the unreachable branches

jacek-prisma · 2026-02-06T10:26:24Z

packages/adapter-mssql/src/mssql.test.ts

+    }
+  }
+
+  describe('with mutex (the fix)', () => {


probably don't need the nested describe here

…NPROG error (#29141) Cleanup of #29119  ## Summary by CodeRabbit * **Bug Fixes** * Fixed race condition in MSSQL transaction handling where commit() or rollback() could fail when queries are in progress. * **Tests** * Added comprehensive test suite for transaction serialization to validate proper operation ordering and error handling.  --------- Co-authored-by: Markus Haave Lund <markus.lund@bekk.no>

jacek-prisma · 2026-02-06T13:30:05Z

Included in #29141

coderabbitai bot reviewed Feb 2, 2026

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MarkusLund force-pushed the fix/adapter-mssql-race-condition branch from f37b4e1 to 4cc03b8 Compare February 5, 2026 09:22

jacek-prisma reviewed Feb 5, 2026

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packages/adapter-mssql/src/mssql.test.ts Outdated Show resolved Hide resolved

fix(adapter-mssql): serialize commit/rollback with mutex

70e179c

MarkusLund force-pushed the fix/adapter-mssql-race-condition branch from 4cc03b8 to 70e179c Compare February 5, 2026 19:57

jacek-prisma reviewed Feb 6, 2026

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jacek-prisma mentioned this pull request Feb 6, 2026

fix(adapter-mssql): acquire mutex in commit/rollback to prevent EREQINPROG error #29141

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fix(adapter-mssql): acquire mutex in commit/rollback to prevent EREQINPROG error#29119

fix(adapter-mssql): acquire mutex in commit/rollback to prevent EREQINPROG error#29119
MarkusLund wants to merge 1 commit intoprisma:mainfrom
MarkusLund:fix/adapter-mssql-race-condition

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