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MDEV-32861 InnoDB hangs when running out of I/O slots

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When the constant OS_AIO_N_PENDING_IOS_PER_THREAD is changed from 256 to 1
and the server is run with the minimum parameters
innodb_read_io_threads=1 and innodb_write_io_threads=2, two hangs
were observed.

tpool::cache<T>::put(T*): Ensure that get() in io_slots::acquire()
will be woken up when the cache previously was empty.

buf_pool_t::io_buf_t::reserve(): Schedule a possibly partial doublewrite
batch so that os_aio_wait_until_no_pending_writes() has a chance of
returning. Add a Boolean parameter and pass wait_for_reads=false inside
buf_page_decrypt_after_read(), because those calls will be executed
inside a read completion callback, and therefore
os_aio_wait_until_no_pending_reads() would block indefinitely.
This commit is contained in:
Marko Mäkelä 2023-11-22 16:54:41 +02:00
parent de31ca6a21
commit 78c9a12c8f
4 changed files with 13 additions and 8 deletions
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11
storage/innobase/buf/buf0buf.cc
View File

@ -414,7 +414,7 @@ static bool buf_page_decrypt_after_read(buf_page_t *bpage,
if (node.space->purpose == FIL_TYPE_TEMPORARY if (node.space->purpose == FIL_TYPE_TEMPORARY
&& innodb_encrypt_temporary_tables) { && innodb_encrypt_temporary_tables) {
slot = buf_pool.io_buf_reserve(); slot = buf_pool.io_buf_reserve(false);
ut_a(slot); ut_a(slot);
slot->allocate(); slot->allocate();
@ -444,7 +444,7 @@ decompress:
return false; return false;
} }
slot = buf_pool.io_buf_reserve(); slot = buf_pool.io_buf_reserve(false);
slot->allocate(); slot->allocate();
decompress_with_slot: decompress_with_slot:
@ -471,7 +471,7 @@ decrypt_failed:
return false; return false;
} }
slot = buf_pool.io_buf_reserve(); slot = buf_pool.io_buf_reserve(false);
slot->allocate(); slot->allocate();
ut_d(fil_page_type_validate(node.space, dst_frame)); ut_d(fil_page_type_validate(node.space, dst_frame));
@ -1513,14 +1513,17 @@ void buf_pool_t::io_buf_t::close()
n_slots= 0; n_slots= 0;
} }
buf_tmp_buffer_t *buf_pool_t::io_buf_t::reserve() buf_tmp_buffer_t *buf_pool_t::io_buf_t::reserve(bool wait_for_reads)
{ {
for (;;) for (;;)
{ {
for (buf_tmp_buffer_t *s= slots, *e= slots + n_slots; s != e; s++) for (buf_tmp_buffer_t *s= slots, *e= slots + n_slots; s != e; s++)
if (s->acquire()) if (s->acquire())
return s; return s;
buf_dblwr.flush_buffered_writes();
os_aio_wait_until_no_pending_writes(); os_aio_wait_until_no_pending_writes();
if (!wait_for_reads)
continue;
for (buf_tmp_buffer_t *s= slots, *e= slots + n_slots; s != e; s++) for (buf_tmp_buffer_t *s= slots, *e= slots + n_slots; s != e; s++)
if (s->acquire()) if (s->acquire())
return s; return s;

2
storage/innobase/buf/buf0flu.cc
View File

@ -702,7 +702,7 @@ static byte *buf_page_encrypt(fil_space_t* space, buf_page_t* bpage, byte* s,
ut_ad(!bpage->zip_size() || !page_compressed); ut_ad(!bpage->zip_size() || !page_compressed);
/* Find free slot from temporary memory array */ /* Find free slot from temporary memory array */
buf_tmp_buffer_t *slot= buf_pool.io_buf_reserve(); buf_tmp_buffer_t *slot= buf_pool.io_buf_reserve(true);
ut_a(slot); ut_a(slot);
slot->allocate(); slot->allocate();
slot->out_buf= NULL; slot->out_buf= NULL;

5
storage/innobase/include/buf0buf.h
View File

@ -2030,7 +2030,8 @@ public:
a delete-buffering operation is pending. Protected by mutex. */ a delete-buffering operation is pending. Protected by mutex. */
buf_page_t watch[innodb_purge_threads_MAX + 1]; buf_page_t watch[innodb_purge_threads_MAX + 1];
/** Reserve a buffer. */ /** Reserve a buffer. */
buf_tmp_buffer_t *io_buf_reserve() { return io_buf.reserve(); } buf_tmp_buffer_t *io_buf_reserve(bool wait_for_reads)
{ return io_buf.reserve(wait_for_reads); }
/** @return whether any I/O is pending */ /** @return whether any I/O is pending */
bool any_io_pending() bool any_io_pending()
@ -2083,7 +2084,7 @@ private:
void close(); void close();
/** Reserve a buffer */ /** Reserve a buffer */
buf_tmp_buffer_t *reserve(); buf_tmp_buffer_t *reserve(bool wait_for_reads);
} io_buf; } io_buf;
/** whether resize() is in the critical path */ /** whether resize() is in the critical path */

3
tpool/tpool_structs.h
View File

@ -138,12 +138,13 @@ public:
{ {
std::unique_lock<std::mutex> lk(m_mtx); std::unique_lock<std::mutex> lk(m_mtx);
assert(!is_full()); assert(!is_full());
const bool was_empty= is_empty();
// put element to the logical end of the array // put element to the logical end of the array
m_cache[--m_pos] = ele; m_cache[--m_pos] = ele;
/* Notify waiters when the cache becomes /* Notify waiters when the cache becomes
not empty, or when it becomes full */ not empty, or when it becomes full */
if (m_pos == 1 || (m_waiters && is_full())) if (was_empty || (is_full() && m_waiters))
m_cv.notify_all(); m_cv.notify_all();
} }