twice already we had cases where sidekiq was doing 100% cpu load if we strace the 2 processes shown maxing out the cpus we get: [pid 17688] futex(0x1e9b6e4, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x1e9b6e0, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b718, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b71c, FUTEX_WAIT_PRIVATE, 759265, NULL) = -1 EAGAIN (Resource temporarily unavailable) [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 0 [pid 17688] futex(0x1e9b6e4, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x1e9b6e0, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b718, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b71c, FUTEX_WAIT_PRIVATE, 759267, NULL) = -1 EAGAIN (Resource temporarily unavailable) [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 0 [pid 17688] sched_yield() = 0 [pid 17688] futex(0x1e9b6e4, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x1e9b6e0, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b718, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b71c, FUTEX_WAIT_PRIVATE, 759269, NULL) = -1 EAGAIN (Resource temporarily unavailable) [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 0 [pid 17688] futex(0x1e9b6e4, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x1e9b6e0, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b718, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b71c, FUTEX_WAIT_PRIVATE, 759271, NULL) = -1 EAGAIN (Resource temporarily unavailable) [pid 17688] write(6, "!", 1) = 1 [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b6e0, FUTEX_WAKE_PRIVATE, 1) = 1 [pid 17688] futex(0x1e9b6e4, FUTEX_WAIT_PRIVATE, 2478513, NULL) = -1 EAGAIN (Resource temporarily unavailable) [pid 17688] futex(0x1e9b6b0, FUTEX_WAKE_PRIVATE, 1) = 0 [pid 17688] sched_yield() = 0 Any advice how to debug the issue? running: discourse-1.9.0.beta8~git1.3bdade8970

a few updates it didnt show any busy jobs while we saw the high cpu usage. Jobs::PullHotlinkedImages was the only job scheduled when we checked why the cpu usage was so high

Were you ever able to pinpoint this issue? We’re seeing the exact same thing on one server. Sidekiq goes to 90% CPU and the only way to get it back to normal is to restart it. It then stays low for a day or so and then it gets stuck at 90% again. ps -T -p says this is happening in manager.rb:27 which is here lib/mini_scheduler/manager.rb main while !@stopped sleep 60 @mutex.synchronize do repair_queue reschedule_orphans ensure_worker_threads end end end @keep_alive_thread = Thread.new do while !@stopped sleep(@manager.keep_alive_duration / 2) @mutex.synchronize { keep_alive } end end ensure_worker_threads end There are no scheduled jobs in Sidekiq.

Use rbtrace to get a better back trace Debugging 100% CPU usage in production Ruby on Rails systems Sam's Spot - Sam saffron's web log

I believe it is on @david’s lower-priority list to have better logging of Sidekiq jobs? I am not sure where that is though.

The plan is to add additional logging to track sidekiq job duration, and various metrics such as DB time and Redis time. We’ll also regularly log “currently running jobs” on a regular basis, to help track things down in the event of a crash. I think it should be ready in 2-3 weeks time.

Ok, this is what I got. I was hoping to spot the culprit more easily but maybe @sam does know better how to interpret these results… ================================== Mode: cpu(1000) Samples: 7994 (0.32% miss rate) GC: 10 (0.13%) ================================== TOTAL (pct) SAMPLES (pct) FRAME 3301 (41.3%) 3300 (41.3%) ActiveModel::LazyAttributeHash#[] 2123 (26.6%) 2123 (26.6%) ActiveRecord::ConnectionAdapters::TransactionState#finalized? 897 (11.2%) 897 (11.2%) ActiveRecord::AttributeMethods::PrimaryKey::ClassMethods#primary_key 787 (9.8%) 786 (9.8%) ActiveModel::Attribute#value 7647 (95.7%) 118 (1.5%) ActiveRecord::AttributeMethods::PrimaryKey#id 3414 (42.7%) 113 (1.4%) ActiveModel::AttributeSet#[] 4400 (55.0%) 104 (1.3%) ActiveRecord::AttributeMethods::Read#_read_attribute 4296 (53.7%) 96 (1.2%) ActiveModel::AttributeSet#fetch_value 2210 (27.6%) 87 (1.1%) ActiveRecord::Transactions#update_attributes_from_transaction_state 55 (0.7%) 55 (0.7%) Nokogiri::XML::Document#decorate 7697 (96.3%) 51 (0.6%) ActiveRecord::Core#== 2234 (27.9%) 24 (0.3%) ActiveRecord::Transactions#sync_with_transaction_state 13 (0.2%) 13 (0.2%) ActionView::PathResolver#find_template_paths 12 (0.2%) 12 (0.2%) PG::Connection#async_exec 11 (0.1%) 11 (0.1%) Nokogiri::XML::XPathContext#register_namespaces 10 (0.1%) 10 (0.1%) (garbage collection) 8 (0.1%) 8 (0.1%) OpenSSL::Buffering#do_write 5 (0.1%) 5 (0.1%) Concurrent::Collection::NonConcurrentMapBackend#get_or_default 5 (0.1%) 5 (0.1%) Concurrent::Collection::NonConcurrentMapBackend#[] 4 (0.1%) 4 (0.1%) Arel::Collectors::PlainString# .parse 3 (0.0%) 3 (0.0%) OpenSSL::SSL::SSLContext#initialize 3 (0.0%) 3 (0.0%) # .blank? 3 (0.0%) 3 (0.0%) Net::Protocol#ssl_socket_connect 4 (0.1%) 3 (0.0%) ActiveModel::Type::Helpers::Numeric#cast 4 (0.1%) 3 (0.0%) Nokogiri::XML::Node#write_to 4 (0.1%) 3 (0.0%) # .reap_connections 4 (0.1%) 3 (0.0%) MiniRacer::Context#timeout

This issue went away and then it came back, and now we finally seem to have found what was going on here. There was a database query hanging which was being triggered from a regular job cleaning up users. It never got to finish because after half an hour it was being killed and restarted. When we performed that task manually the issue was gone.

Locking issues in sidekiq jobs?

Product Support

sam (Sam Saffron) January 2, 2019, 7:45pm 4

Use rbtrace to get a better back trace

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Locking issues in sidekiq jobs?

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