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rocksdb/db/compaction/subcompaction_state.cc
Josh Kang 3d99378791 Fix table handle leak (#14469)
Summary:
Fix leaked table cache entries that cause `TEST_VerifyNoObsoleteFilesCached` assertion failure during `DB::Close()` in ASAN crash test builds (T258745630):
```
File 126519 is not live nor quarantined
Assertion `cached_file_is_live_or_quar' failed.
```

When a compaction fails *after* `VerifyOutputFiles` succeeds (e.g., at `VerifyCompactionRecordCounts`), the overall `compact_->status` is set to error but each subcompaction's individual `status` remains OK. `SubcompactionState::Cleanup` only checked the individual subcompaction status, so it skipped calling `ReleaseObsolete` on the output files' table cache entries — leaking them.

Normally, `Close()`'s backstop (`FindObsoleteFiles(force=true)` + `PurgeObsoleteFiles`) would catch this by finding the orphan file on disk, evicting the cache entry, and deleting the file. However, `FindObsoleteFiles` calls `FaultInjectionTestFS::GetChildren` which can fail under metadata read fault injection (`--open_metadata_read_fault_one_in=8`). The error is silently ignored (`s.PermitUncheckedError()` in db_impl_files.cc:199), so the orphan file is never found and the leaked cache entry is never evicted.

The `Cleanup` bug is latent and predates recent changes. PR https://github.com/facebook/rocksdb/issues/14433 added `verify_output_flags` randomization to the crash test, and PR https://github.com/facebook/rocksdb/issues/14456 fixed false-positive corruptions that https://github.com/facebook/rocksdb/issues/14433 caused. Before https://github.com/facebook/rocksdb/issues/14456, `VerifyOutputFiles` would produce false corruption errors that *accidentally prevented the leak* by setting the subcompaction status to non-OK.

### How it triggers

**Step 1 — VerifyOutputFiles adds cache entries for compaction output files:**
```
CompactionJob::Run()
  RunSubcompactions()              // all subcompactions succeed
                                   // output file 12 written to disk
                                   // each sub_compact.status = OK
  SyncOutputDirectories()          // status = OK
  VerifyOutputFiles()
    for each output_file:
      table_cache()->NewIterator(output_file.meta)
        FindTable()
          cache->Insert(file_number=12)   // <<< ENTRY ADDED TO TABLE CACHE
        return iterator holding handle
      delete iter                          // releases handle, entry stays in LRU
    // status = OK
```

**Step 2 — A post-verification step fails, overall status set but NOT subcompaction status:**
```
CompactionJob::Run()
  VerifyCompactionRecordCounts()   // returns Status::Corruption(...)
  FinalizeCompactionRun(status=Corruption)
    compact_->status = Corruption  // <<< OVERALL status = error
    // each sub_compact.status is still OK!
```

**Step 3 — Install skips InstallCompactionResults (file 12 never enters a Version):**
```
CompactionJob::Install()
  status = compact_->status        // Corruption
  if (status.ok())                 // FALSE
    InstallCompactionResults()     // <<< SKIPPED — file 12 not in any version
```

**Step 4 — CleanupCompaction skips ReleaseObsolete (THE BUG):**
```
CompactionJob::CleanupCompaction()
  for each sub_compact:
    sub_compact.Cleanup(table_cache)
      if (!status.ok())            // checks sub_compact.status = OK
                                   // <<< FALSE — individual status is OK!
        ReleaseObsolete(...)       // <<< NEVER CALLED — cache entry leaked!
```

**Step 5 — Metadata read fault prevents backstop from finding the orphan:**

`FindObsoleteFiles(force=true)` calls `GetChildren()` to scan the DB directory.
`FaultInjectionTestFS::GetChildren` injects a metadata read error
(`--open_metadata_read_fault_one_in=8`). The error is silently ignored
(`s.PermitUncheckedError()`), so the directory listing is empty and the orphan
file is never found. This happens both in the post-compaction cleanup
(`BackgroundCallCompaction`) and in `Close()`'s backstop:
```
FindObsoleteFiles(force=true)
  fs->GetChildren(path, ...)       // returns IOError (fault injected)
  s.PermitUncheckedError();        // error silently ignored
  // files vector is empty — orphan file 12 not found
PurgeObsoleteFiles()               // nothing to do — no Evict called
```

**Step 6 — Assertion fires during Close():**
```
CloseHelper()
  FindObsoleteFiles(force=true)    // GetChildren fails again → orphan missed
  PurgeObsoleteFiles()             // nothing to evict
  TEST_VerifyNoObsoleteFilesCached()
    for each cache entry:
      file_number = 12
      live_and_quar_files.find(12) == end()  // NOT in any version!
      >>> assert(cached_file_is_live_or_quar) FAILS <<<
```

**Crash test call stack:**
```
frame https://github.com/facebook/rocksdb/issues/9:  __assert_fail_base("cached_file_is_live_or_quar", "db_impl_debug.cc", 389)
frame https://github.com/facebook/rocksdb/issues/11: DBImpl::TEST_VerifyNoObsoleteFilesCached()::lambda  // finds leaked entry
frame https://github.com/facebook/rocksdb/issues/18: LRUCacheShard::ApplyToSomeEntries(...)              // iterating cache shard
frame https://github.com/facebook/rocksdb/issues/19: ShardedCache::ApplyToAllEntries(...)                // iterating all shards
frame https://github.com/facebook/rocksdb/issues/20: DBImpl::TEST_VerifyNoObsoleteFilesCached()          // the verification
frame https://github.com/facebook/rocksdb/issues/21: DBImpl::CloseHelper()                               // during Close
frame https://github.com/facebook/rocksdb/issues/22: DBImpl::CloseImpl()
frame https://github.com/facebook/rocksdb/issues/23: DBImpl::Close()
frame https://github.com/facebook/rocksdb/issues/24: StressTest::Reopen()                                // crash test reopen
frame https://github.com/facebook/rocksdb/issues/25: StressTest::OperateDb()                             // worker thread
```

### Fix

Pass the overall `compact_->status` to `SubcompactionState::Cleanup` and call
`ReleaseObsolete` when *either* the subcompaction status or the overall status
is non-OK:
```cpp
// Before:
if (!status.ok()) { ReleaseObsolete(...); }

// After:
if (!status.ok() || !overall_status.ok()) { ReleaseObsolete(...); }
```

## Key changes

- **`SubcompactionState::Cleanup`**: Now takes an `overall_status` parameter and calls `ReleaseObsolete` when *either* the subcompaction status or the overall compaction status is non-OK.
- **`CompactionJob::CleanupCompaction`**: Passes `compact_->status` (the overall status) to each subcompaction's `Cleanup`.
- **Sync point**: Added `CompactionJob::Run():AfterVerifyOutputFiles` for error injection in tests.
- **Unit test**: `DBCompactionTest.LeakedTableCacheEntryOnCompactionFailure` uses `FaultInjectionTestFS` to reproduce the crash test scenario — injects error after `VerifyOutputFiles` and deactivates the filesystem so `GetChildren` fails in `FindObsoleteFiles`, preventing the backstop from evicting the leaked cache entry.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/14469

Test Plan:
- `DBCompactionTest.LeakedTableCacheEntryOnCompactionFailure`:
  - **Without fix (ASAN)**: assertion fires during `Close()` — `File 12 is not live nor quarantined`
  - **With fix (ASAN)**: passes — `ReleaseObsolete` properly cleans up the cache entry
  - **With fix (non-ASAN)**: passes
```
$ COMPILE_WITH_ASAN=1 make -j db_compaction_test
$ ./db_compaction_test --gtest_filter="DBCompactionTest.LeakedTableCacheEntryOnCompactionFailure"
[  PASSED  ] 1 test.
```

Reviewed By: xingbowang

Differential Revision: D97190944

Pulled By: joshkang97

fbshipit-source-id: fdfd481cc1e192803cfb7d64052ccb9162c21b94
2026-03-23 10:50:43 -07:00

121 lines
4.3 KiB
C++

// Copyright (c) Meta Platforms, Inc. and affiliates.
//
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/compaction/subcompaction_state.h"
#include "rocksdb/sst_partitioner.h"
namespace ROCKSDB_NAMESPACE {
void SubcompactionState::AggregateCompactionOutputStats(
InternalStats::CompactionStatsFull& internal_stats) const {
// Outputs should be closed. By extension, any files created just for
// range deletes have already been written also.
assert(compaction_outputs_.HasBuilder() == false);
assert(proximal_level_outputs_.HasBuilder() == false);
// FIXME: These stats currently include abandonned output files
// assert(compaction_outputs_.stats_.num_output_files ==
// compaction_outputs_.outputs_.size());
// assert(proximal_level_outputs_.stats_.num_output_files ==
// proximal_level_outputs_.outputs_.size());
internal_stats.output_level_stats.Add(compaction_outputs_.stats_);
if (proximal_level_outputs_.HasOutput()) {
internal_stats.has_proximal_level_output = true;
internal_stats.proximal_level_stats.Add(proximal_level_outputs_.stats_);
}
}
OutputIterator SubcompactionState::GetOutputs() const {
return OutputIterator(proximal_level_outputs_.outputs_,
compaction_outputs_.outputs_);
}
void SubcompactionState::Cleanup(Cache* cache, const Status& overall_status) {
proximal_level_outputs_.Cleanup();
compaction_outputs_.Cleanup();
if (!status.ok() || !overall_status.ok()) {
for (const auto& out : GetOutputs()) {
// If this file was inserted into the table cache then remove it here
// because this compaction was not committed. This is not strictly
// required because of a backstop TableCache::Evict() in
// PurgeObsoleteFiles() but is our opportunity to apply
// uncache_aggressiveness. TODO: instead, put these files into the
// VersionSet::obsolete_files_ pipeline so that they don't have to
// be picked up by scanning the DB directory.
TableCache::ReleaseObsolete(
cache, out.meta.fd.GetNumber(), nullptr /*handle*/,
compaction->mutable_cf_options().uncache_aggressiveness);
}
}
// TODO: sub_compact.io_status is not checked like status. Not sure if thats
// intentional. So ignoring the io_status as of now.
io_status.PermitUncheckedError();
}
Slice SubcompactionState::SmallestUserKey() const {
if (proximal_level_outputs_.HasOutput()) {
Slice a = compaction_outputs_.SmallestUserKey();
Slice b = proximal_level_outputs_.SmallestUserKey();
if (a.empty()) {
return b;
}
if (b.empty()) {
return a;
}
const Comparator* user_cmp =
compaction->column_family_data()->user_comparator();
if (user_cmp->Compare(a, b) > 0) {
return b;
} else {
return a;
}
} else {
return compaction_outputs_.SmallestUserKey();
}
}
Slice SubcompactionState::LargestUserKey() const {
if (proximal_level_outputs_.HasOutput()) {
Slice a = compaction_outputs_.LargestUserKey();
Slice b = proximal_level_outputs_.LargestUserKey();
if (a.empty()) {
return b;
}
if (b.empty()) {
return a;
}
const Comparator* user_cmp =
compaction->column_family_data()->user_comparator();
if (user_cmp->Compare(a, b) < 0) {
return b;
} else {
return a;
}
} else {
return compaction_outputs_.LargestUserKey();
}
}
Status SubcompactionState::AddToOutput(
const CompactionIterator& iter, bool use_proximal_output,
const CompactionFileOpenFunc& open_file_func,
const CompactionFileCloseFunc& close_file_func,
const ParsedInternalKey& prev_iter_output_internal_key) {
// update target output
current_outputs_ =
use_proximal_output ? &proximal_level_outputs_ : &compaction_outputs_;
return current_outputs_->AddToOutput(iter, open_file_func, close_file_func,
prev_iter_output_internal_key);
}
} // namespace ROCKSDB_NAMESPACE