Mute ydb/tests/functional/nbs/test_nbs.py.TestNbs.test_nbs_disk_creation_name_with_symbols in main

[ydbot]

Mute:
ydb/tests/functional/nbs/test_nbs.py.TestNbs.test_nbs_disk_creation_name_with_symbols

Branch:
main

Build type:
relwithdebinfo

Owner: TEAM:@ydb-platform/nbs

About this issue

• Auto-created by the mute workflow.
• Bot closes when all listed tests are unmuted or no longer exist.
• Close as Completed to trigger fast-unmute.
• mute_rules.md — full details.

Summary history:
test_nbs.py.TestNbs.test_nbs_disk_creation_name_with_symbols: Flaky(2026-07-14)->Passed(2026-07-15)->Flaky(2026-07-17) last 1 days, at 2026-07-14:2026-07-17: success_rate 96.6%, p-86, f-3, m-0, s-0, total-89

Test run history: link

More info in dashboard

[ydbot]

LLM instructions

Classify: TEST_ISSUE | YDB_ISSUE | TEST_INFRA_ISSUE
- YDB_ISSUE: product bug under ydb/core, ydb/library, etc.
- TEST_ISSUE: test logic, stale refs in helpers/workloads, missing waits. Fixture/harness PR
  that exposed a latent test bug → TEST_ISSUE; Responsible = fix path, not PR author.
- TEST_INFRA_ISSUE: shared harness/runner/CI broken for many unrelated tests. One directory /
  one test pattern → usually TEST_ISSUE, not TEST_INFRA_ISSUE.

Find root cause and introducing commit/PR; severity HIGH/MEDIUM/LOW; propose a fix.
In Root Cause list Suspect PR(s) most-likely-first (#12345 + why; tie to code/regression window).

Summary history (success_rate, p-*, f-*, total-*, dates): 50% often = runs before vs after a
merge, not a timing race. Compare failing tests with sibling tests (same fixture, still pass).

After fixture stop_driver(): "Driver was stopped" / "Topic client closed" → check stale driver
snapshot in workload/helpers before suggesting retries, sleeps, or graceful-shutdown revert.

VERIFY/SANITIZER — use status_description in exactly 3 lines:
  VERIFY failed (<ISO_UTC>): / ydb/.../file:line / assertion text (no stack frames, no +0x...)

Responsible (NOT issue-body Owner: — that is mute assignee only):
Pick team for the root-cause fix (first match):
  a) Fix path → .github/TESTOWNERS longest prefix (wins if PR exposed latent test bug)
  b) YDB_ISSUE → TESTOWNERS for broken ydb/... path
  c) Harness itself wrong → introducing PR author team
  d) Pure CI/Actions, no product commit → area/engineering
Map slug → area/... via .github/config/owner_area_mapping.json
Rules: root cause > Owner; commit from A exposing bug in B → B fixes; use area/queryprocessor not area/@ydb-platform/...

Reply exactly:
## Analysis
### Classification:
#### Error type: <TYPE>
#### Severity: <LEVEL>
#### Responsible: area/<team>
### Root Cause
<what broke>
Suspect PR(s), ordered by causality (most likely first):
1. #<pr> — <why>
### Suggested Fix
<fix or investigation>
### Summary
<2-4 sentences: failure, root cause, who fixes, next step>

Links to recent failed test runs

test	status	type	last_run	history	run	stderr	stdout	log	logsdir
test_nbs.py.TestNbs.test_nbs_disk_creation_name_with_symbols	failure	N/A	2026-07-17 12:04:43 UTC	link	link	n/a	n/a	link	link

[robot-vibe-db]

Analysis

Classification:

Error type: YDB_ISSUE

Severity: LOW

Responsible: area/nbs

Root Cause

The NBS dynamic slot process (slot_1) crashes with SIGSEGV (exit code -11) during cluster shutdown in the test teardown phase (self.cluster.stop()).

The root cause is a lifecycle bug in TPartitionActor::PassAway() (partition_direct_actor.cpp). The PassAway() method was overridden to only log a message but did not call Die() or the base class PassAway(). This made the partition actor "immortal" — when the actor system requests shutdown via PassAway(), the actor stays alive while the rest of the system (vhost server, DDisk sessions, BlobStorage) is being torn down. The still-alive actor then accesses already-freed resources, causing SIGSEGV.

The test uses a hardcoded disk_id="disk%1" with a % character. While the % character itself is handled safely (passed as %s arguments in all logging/formatting paths), the fixed disk ID (vs. random IDs in sibling tests like test_nbs_disk_creation) produces deterministic execution timing, making this test more susceptible to the shutdown race window.

The bug was latent since TPartitionActor was introduced. Recent NBS changes around DDisk session handling and shutdown recovery (PRs #45705, #46041, #46153, #45894) may have altered the shutdown sequence timing, making the race more likely to trigger in CI.

Suspect PR(s), ordered by causality (most likely first):

1. [NBS] Fix TPartitionActor immortality #46912 — This is the FIX, not the introduction. Merged 2026-07-17 12:42 UTC, after the test failure at 12:04 UTC. It removes the broken PassAway() override and ensures proper actor termination through OnDetach() and OnTabletDead() calling Die().
2. NBS-7459: block PBuffer cleanup until vchunk restore completes #45705 — NBS-7459: block PBuffer cleanup until vchunk restore completes (merged 2026-07-13). Changed cleanup ordering in TFastPathService::FinishPBufferCleanup(), which may have altered shutdown timing to expose the latent PassAway() bug more frequently.

Suggested Fix

PR #46912 ([NBS] Fix TPartitionActor immortality) has already been merged into main as of 2026-07-17 12:42 UTC. This fix:

• Removes the broken PassAway() override that silently swallowed the shutdown request
• Adds proper logging to OnDetach() and OnTabletDead() for debugging future lifecycle issues

Next steps:

1. Monitor the test over the next 2-3 days to confirm it stabilizes after PR [NBS] Fix TPartitionActor immortality #46912
2. If the test continues to flake after the fix is picked up by CI, investigate the vhost server shutdown path for additional lifecycle issues (the socket path /tmp/disk%1.sock and the vhost endpoint teardown sequence)
3. Once confirmed stable, unmute the test by closing this issue as Completed

Summary

test_nbs_disk_creation_name_with_symbols fails intermittently (96.6% success rate, 3 failures out of 89 runs) due to the NBS partition actor's PassAway() override not actually terminating the actor during shutdown, causing SIGSEGV from use-after-free. This latent bug was recently exposed by NBS shutdown sequence changes. The fix was already merged in PR #46912 — the test should stabilize once CI picks up the new code. The responsible team is area/nbs (@ydb-platform/nbs).

[robot-vibe-db]

Full analysis log

Analysis performed by claude, claude-opus-4-6.