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Reduce GC CPU usage in storage v2

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Reviewers: mtomic, teon.banek

Reviewed By: mtomic

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D2313
This commit is contained in:
Matej Ferencevic 2019-08-21 14:16:33 +02:00
parent 21d461e77d
commit a9d2f4842f
1 changed files with 13 additions and 2 deletions
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15
src/storage/v2/storage.cpp
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@ -932,6 +932,13 @@ void Storage::CollectGarbage() {
deleted_vertices_->swap(current_deleted_vertices);
deleted_edges_->swap(current_deleted_edges);
// Flag that will be used to determine whether the Index GC should be run. It
// should be run when there were any items that were cleaned up (there were
// updates between this run of the GC and the previous run of the GC). This
// eliminates high CPU usage when the GC doesn't have to clean up anything.
bool run_index_cleanup =
!committed_transactions_->empty() || !garbage_undo_buffers_->empty();
while (true) {
// We don't want to hold the lock on commited transactions for too long,
// because that prevents other transactions from committing.
@ -1020,7 +1027,11 @@ void Storage::CollectGarbage() {
// we're sure that none of the vertices from `current_deleted_vertices`
// appears in an index, and we can safely remove the from the main storage
// after the last currently active transaction is finished.
RemoveObsoleteEntries(&indices_, oldest_active_start_timestamp);
if (run_index_cleanup) {
// This operation is very expensive as it traverses through all of the items
// in every index every time.
RemoveObsoleteEntries(&indices_, oldest_active_start_timestamp);
}
{
std::unique_lock<utils::SpinLock> guard(engine_lock_);
@ -1048,7 +1059,7 @@ void Storage::CollectGarbage() {
while (true) {
auto garbage_undo_buffers_ptr = garbage_undo_buffers_.Lock();
if (garbage_undo_buffers_ptr->empty() ||
garbage_undo_buffers_ptr->front().first >=
garbage_undo_buffers_ptr->front().first >
oldest_active_start_timestamp) {
break;
}