Only flush after recovery for retryable IOError (facebook#11880)

Summary:
facebook#11872 causes a unit test to start failing with the error message below. The cause is that the additional call to `FlushAllColumnFamilies()` in `DBImpl::ResumeImpl()` can run while DB is closing. More detailed explanation: there are two places where we call `ResumeImpl()`:

1. in `ErrorHandler::RecoverFromBGError`, for manual resume or recovery from errors like OutOfSpace through sst file manager, and
2. in `Errorhandler::RecoverFromRetryableBGIOError`, for error recovery from errors like flush failure due to retryable IOError. This is tracked by `ErrorHandler::recovery_thread_`.

Here is how DB close waits for error recovery: https://github.com/facebook/rocksdb/blob/49da91ec097b4efcd8a8e4dc1b287e9f81eb4093/db/db_impl/db_impl.cc#L540-L543

`CancelErrorRecovery()` waits until `recovery_thread_` finishes and `IsRecoveryInProgress()` checks the `recovery_in_prog_` flag. The additional call to `FlushAllColumnFamilies()` in `ResumeImpl()` happens after it clears bg error and the `recovery_in_prog_` flag: https://github.com/facebook/rocksdb/blob/49da91ec097b4efcd8a8e4dc1b287e9f81eb4093/db/db_impl/db_impl.cc#L436-L463. So if `ResumeImpl()` is called in `RecoverFromBGError()`, we can have a thread running `FlushAllColumnFamilies()` while DB is closing and thought that recovery is done.

The fix is to only do the additional call to `FlushAllColumnFamilies()` when doing error recovery through `Errorhandler::RecoverFromRetryableBGIOError` by setting flags in `DBRecoverContext`.

Pull Request resolved: facebook#11880

Test Plan:
`gtest-parallel --repeat=100 --workers=4 ./error_handler_fs_test --gtest_filter="*AutoRecoverFlushError*"` reproduces the error pretty reliably.

```[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from DBErrorHandlingFSTest
[ RUN      ] DBErrorHandlingFSTest.AutoRecoverFlushError
error_handler_fs_test: db/column_family.cc:1618: rocksdb::ColumnFamilySet::~ColumnFamilySet(): Assertion `last_ref' failed.
Received signal 6 (Aborted)
...
facebook#10 0x00007fac4409efd6 in __GI___assert_fail (assertion=0x7fac452c0afa "last_ref", file=0x7fac452c9fb5 "db/column_family.cc", line=1618, function=0x7fac452cb950 "rocksdb::ColumnFamilySet::~ColumnFamilySet()") at assert.c:101
101     in assert.c
facebook#11 0x00007fac44b5324f in rocksdb::ColumnFamilySet::~ColumnFamilySet (this=0x7b5400000000) at db/column_family.cc:1618
1618        assert(last_ref);
facebook#12 0x00007fac44e0f047 in std::default_delete<rocksdb::ColumnFamilySet>::operator() (this=0x7b5800000940, __ptr=0x7b5400000000) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:85
85              delete __ptr;
facebook#13 std::__uniq_ptr_impl<rocksdb::ColumnFamilySet, std::default_delete<rocksdb::ColumnFamilySet> >::reset (this=0x7b5800000940, __p=0x0) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:182
182               _M_deleter()(__old_p);
facebook#14 std::unique_ptr<rocksdb::ColumnFamilySet, std::default_delete<rocksdb::ColumnFamilySet> >::reset (this=0x7b5800000940, __p=0x0) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:456
456             _M_t.reset(std::move(__p));
facebook#15 rocksdb::VersionSet::~VersionSet (this=this@entry=0x7b5800000900) at db/version_set.cc:5081
5081      column_family_set_.reset();
facebook#16 0x00007fac44e0f97a in rocksdb::VersionSet::~VersionSet (this=0x7b5800000900) at db/version_set.cc:5078
5078    VersionSet::~VersionSet() {
facebook#17 0x00007fac44bf0b2f in std::default_delete<rocksdb::VersionSet>::operator() (this=0x7b8c00000068, __ptr=0x7b5800000900) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:85
85              delete __ptr;
facebook#18 std::__uniq_ptr_impl<rocksdb::VersionSet, std::default_delete<rocksdb::VersionSet> >::reset (this=0x7b8c00000068, __p=0x0) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:182
182               _M_deleter()(__old_p);
facebook#19 std::unique_ptr<rocksdb::VersionSet, std::default_delete<rocksdb::VersionSet> >::reset (this=0x7b8c00000068, __p=0x0) at /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/unique_ptr.h:456
456             _M_t.reset(std::move(__p));
facebook#20 rocksdb::DBImpl::CloseHelper (this=this@entry=0x7b8c00000000) at db/db_impl/db_impl.cc:676
676       versions_.reset();
facebook#21 0x00007fac44bf1346 in rocksdb::DBImpl::CloseImpl (this=0x7b8c00000000) at db/db_impl/db_impl.cc:720
720     Status DBImpl::CloseImpl() { return CloseHelper(); }
facebook#22 rocksdb::DBImpl::~DBImpl (this=this@entry=0x7b8c00000000) at db/db_impl/db_impl.cc:738
738       closing_status_ = CloseImpl();
facebook#23 0x00007fac44bf2bba in rocksdb::DBImpl::~DBImpl (this=0x7b8c00000000) at db/db_impl/db_impl.cc:722
722     DBImpl::~DBImpl() {
facebook#24 0x00007fac455444d4 in rocksdb::DBTestBase::Close (this=this@entry=0x7b6c00000000) at db/db_test_util.cc:678
678       delete db_;
facebook#25 0x00007fac455455fb in rocksdb::DBTestBase::TryReopen (this=this@entry=0x7b6c00000000, options=...) at db/db_test_util.cc:707
707       Close();
facebook#26 0x00007fac45543459 in rocksdb::DBTestBase::Reopen (this=0x7ffed74b79a0, options=...) at db/db_test_util.cc:670
670       ASSERT_OK(TryReopen(options));
facebook#27 0x00000000004f2522 in rocksdb::DBErrorHandlingFSTest_AutoRecoverFlushError_Test::TestBody (this=this@entry=0x7b6c00000000) at db/error_handler_fs_test.cc:1224
1224      Reopen(options);
```

Reviewed By: jowlyzhang

Differential Revision: D49579701

Pulled By: cbi42

fbshipit-source-id: 3fc8325e6dde7e7faa8bcad95060cb4e26eda638

db/db_impl/db_impl.cc

@@ -453,7 +453,7 @@ Status DBImpl::ResumeImpl(DBRecoverContext context) {
   if (shutdown_initiated_) {
     s = Status::ShutdownInProgress();
   }
-  if (s.ok()) {
+  if (s.ok() && context.flush_after_recovery) {
     // Since we drop all non-recovery flush requests during recovery,
     // and new memtable may fill up during recovery,
     // schedule one more round of flush.
@@ -472,14 +472,16 @@ Status DBImpl::ResumeImpl(DBRecoverContext context) {
     // FlushAllColumnFamilies releases and re-acquires mutex.
     if (shutdown_initiated_) {
       s = Status::ShutdownInProgress();
-    } else {
-      for (auto cfd : *versions_->GetColumnFamilySet()) {
-        SchedulePendingCompaction(cfd);
-      }
-      MaybeScheduleFlushOrCompaction();
     }
   }
 
+  if (s.ok()) {
+    for (auto cfd : *versions_->GetColumnFamilySet()) {
+      SchedulePendingCompaction(cfd);
+    }
+    MaybeScheduleFlushOrCompaction();
+  }
+
   // Wake up any waiters - in this case, it could be the shutdown thread
   bg_cv_.SignalAll();
 

db/error_handler.cc

@@ -679,6 +679,7 @@ void ErrorHandler::RecoverFromRetryableBGIOError() {
     return;
   }
   DBRecoverContext context = recover_context_;
+  context.flush_after_recovery = true;
   int resume_count = db_options_.max_bgerror_resume_count;
   uint64_t wait_interval = db_options_.bgerror_resume_retry_interval;
   uint64_t retry_count = 0;

db/error_handler.h

@@ -19,10 +19,13 @@ class DBImpl;
 // FlushReason, which tells the flush job why this flush is called.
 struct DBRecoverContext {
   FlushReason flush_reason;
+  bool flush_after_recovery;
 
-  DBRecoverContext() : flush_reason(FlushReason::kErrorRecovery) {}
-
-  DBRecoverContext(FlushReason reason) : flush_reason(reason) {}
+  DBRecoverContext()
+      : flush_reason(FlushReason::kErrorRecovery),
+        flush_after_recovery(false) {}
+  DBRecoverContext(FlushReason reason)
+      : flush_reason(reason), flush_after_recovery(false) {}
 };
 
 class ErrorHandler {