mirrors/dragonfly
1
0
Fork 0
mirror of https://github.com/dragonflydb/dragonfly.git synced 2025-05-10 18:05:44 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

feat: introduce 'debug tx' command and periodic overload logs (#2333)

Browse source 
This command shows the current state of transaction queues,
specifically how many armed (ready to run) transactions there,
how loaded these queue are and how many locks there are in each shard.

In addition, if a tx queue becomes too long, we will output warning logs about
the state of the queue, in order to be able to identify
the bottlenecks post-factum.

Signed-off-by: Roman Gershman <roman@dragonflydb.io>
This commit is contained in:
Roman Gershman 2023-12-25 11:48:55 +02:00 • committed by GitHub
parent a360b308c9
commit ce7497071c
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
6 changed files with 146 additions and 52 deletions
Download patch file Download diff file Expand all files Collapse all files

23
src/server/transaction.cc
View file

@ -14,6 +14,9 @@
#include "server/journal/journal.h"
#include "server/server_state.h"
ABSL_FLAG(uint32_t, tx_queue_warning_len, 30,
"Length threshold for warning about long transaction queue");
namespace dfly {
using namespace std;
@ -1098,7 +1101,25 @@ pair<bool, bool> Transaction::ScheduleInShard(EngineShard* shard) {
TxQueue::Iterator it = txq->Insert(this);
DCHECK_EQ(TxQueue::kEnd, sd.pq_pos);
sd.pq_pos = it;
unsigned q_limit = absl::GetFlag(FLAGS_tx_queue_warning_len);
if (txq->size() > q_limit) {
static thread_local time_t last_log_time = 0;
// TODO: glog provides LOG_EVERY_T, which uses precise clock.
// We should introduce inside helio LOG_PERIOD_ATLEAST macro that takes seconds and
// uses low precision clock.
time_t now = time(nullptr);
if (now >= last_log_time + 10) {
last_log_time = now;
EngineShard::TxQueueInfo info = shard->AnalyzeTxQueue();
LOG(WARNING) << "TxQueue is too long. Tx count:" << info.tx_total
<< ", armed:" << info.tx_armed << ", runnable:" << info.tx_runnable
<< ", total locks: " << info.total_locks
<< ", contended locks: " << info.contended_locks << "\n"
<< "max contention score: " << info.max_contention_score
<< ", lock: " << info.max_contention_lock_name;
}
}
DVLOG(1) << "Insert into tx-queue, sid(" << sid << ") " << DebugId() << ", qlen " << txq->size();
return {true, lock_granted};
@ -1330,6 +1351,8 @@ inline uint32_t Transaction::DecreaseRunCnt() {
}
bool Transaction::IsGlobal() const {
// Please note that a transaction can be non-global even if multi_->mode == GLOBAL.
// It happens when a transaction is squashed and switches to execute differrent commands.
return global_;
}