Prometheus monitoring
Contents
Prometheus monitoring¶
Prometheus is a widely popular tool for monitoring and alerting a wide variety of
systems. A distributed cluster offers a number of Prometheus metrics if the
prometheus_client package is installed. The metrics are exposed in Prometheus’
text-based format at the /metrics endpoint on both schedulers and workers.
Available metrics¶
Apart from the metrics exposed per default by the prometheus_client, schedulers and workers expose a number of Dask-specific metrics.
Scheduler metrics¶
The scheduler exposes the following metrics about itself:
- dask_scheduler_clients
Number of clients connected
- dask_scheduler_client_connections_added_total
Total number of client connections added to the scheduler
Note
This metric does not count distinct clients. If a client disconnects and reconnects later on, it will be counted twice.
- dask_scheduler_client_connections_removed_total
Total number of client connections removed from the scheduler
Note
This metric does not count distinct clients. If a client disconnects, then reconnects and disconnects again, it will be counted twice.
- dask_scheduler_desired_workers
Number of workers scheduler needs for task graph
- dask_scheduler_gil_contention_seconds_total
Value representing cumulative total of potential GIL contention, in the form of cumulative seconds during which any thread held the GIL locked. Other threads may or may not have been actually trying to acquire the GIL in the meantime.
Note
Requires
gilknockerto be installed, anddistributed.admin.system-monitor.gil.enabledconfiguration to be set.- dask_scheduler_gc_collection_seconds_total
Total time spent on garbage dask_scheduler_gc_collection_seconds_total
Note
Due to measurement overhead, this metric only measures time spent on garbage collection for generation=2
- dask_scheduler_workers
Number of workers known by scheduler
- dask_scheduler_workers_added_total
Total numbers of workers added to the scheduler
- dask_scheduler_workers_removed_total
Total number of workers removed from the scheduler
- dask_scheduler_last_time_total
Cumulative SystemMonitor time
- dask_scheduler_tasks
Number of tasks known by scheduler
- dask_scheduler_tasks_suspicious_total
Total number of times a task has been marked suspicious
- dask_scheduler_tasks_forgotten_total
Total number of processed tasks no longer in memory and already removed from the scheduler job queue.
Note
Task groups on the scheduler which have all tasks in the forgotten state are not included.
- dask_scheduler_tasks_compute_seconds_total
Total time (per prefix) spent computing tasks
- dask_scheduler_tasks_transfer_seconds_total
Total time (per prefix) spent transferring
- dask_scheduler_tasks_output_bytes
Current size of in memory tasks, broken down by task prefix, without duplicates. Note that when a task output is transferred between worker, you’ll typically end up with a duplicate, so this measure is going to be lower than the actual cluster-wide managed memory. See also
dask_worker_memory_bytes, which does count duplicates.- dask_scheduler_task_groups
Number of task groups known by scheduler
- dask_scheduler_prefix_state_totals_total
Accumulated count of task prefix in each state
- dask_scheduler_tick_count_total
Total number of ticks observed since the server started
- dask_scheduler_tick_duration_maximum_seconds
Maximum tick duration observed since Prometheus last scraped metrics. If this is significantly higher than what’s configured in
distributed.admin.tick.interval(default: 20ms), it highlights a blocked event loop, which in turn hampers timely task execution and network comms.
Semaphore metrics¶
The following metrics about Semaphore objects are available on the
scheduler:
- dask_semaphore_max_leases
Maximum leases allowed per semaphore.
Note
This will be constant for each semaphore during its lifetime.
- dask_semaphore_active_leases
Amount of currently active leases per semaphore
- dask_semaphore_pending_leases
Amount of currently pending leases per semaphore
- dask_semaphore_acquire_total
Total number of leases acquired per semaphore
- dask_semaphore_release_total
Total number of leases released per semaphore
Note
If a semaphore is closed while there are still leases active, this count will not equal
dask_semaphore_acquire_totalafter execution.- dask_semaphore_average_pending_lease_time_s
Exponential moving average of the time it took to acquire a lease per semaphore
Note
This only includes time spent on scheduler side, it does not include time spent on communication.
Note
This average is calculated based on order of leases instead of time of lease acquisition.
Work-stealing metrics¶
If Work Stealing is enabled, the scheduler exposes these metrics:
- dask_stealing_request_count_total
Total number of stealing requests
- dask_stealing_request_cost_total
Total cost of stealing requests
Worker metrics¶
The worker exposes these metrics about itself:
- dask_worker_tasks
Number of tasks at worker
- dask_worker_threads
Number of worker threads
- dask_worker_gil_contention_seconds_total
Value representing cumulative total of potential GIL contention, in the form of cumulative seconds during which any thread held the GIL locked. Other threads may or may not have been actually trying to acquire the GIL in the meantime.
Note
Requires
gilknockerto be installed, anddistributed.admin.system-monitor.gil.enabledconfiguration to be set.- dask_worker_gc_collection_seconds_total
Total time spent on garbage dask_scheduler_gc_collection_seconds_total
Note
Due to measurement overhead, this metric only measures time spent on garbage collection for generation=2
- dask_worker_latency_seconds
Latency of worker connection
- dask_worker_memory_bytes
Memory breakdown
- dask_worker_transfer_incoming_bytes
Total size of open data transfers from other workers
- dask_worker_transfer_incoming_count
Number of open data transfers from other workers
- dask_worker_transfer_incoming_count_total
Total number of data transfers from other workers since the worker was started
- dask_worker_transfer_outgoing_bytes
Size of open data transfers to other workers
- dask_worker_transfer_outgoing_bytes_total
Total size of open data transfers to other workers since the worker was started
- dask_worker_transfer_outgoing_count
Number of open data transfers to other workers
- dask_worker_transfer_outgoing_count_total
Total number of data transfers to other workers since the worker was started
- dask_worker_concurrent_fetch_requests
Deprecated: This metric has been renamed to
dask_worker_transfer_incoming_count.- dask_worker_tick_count_total
Total number of ticks observed since the server started
- dask_worker_tick_duration_maximum_seconds
Maximum tick duration observed since Prometheus last scraped metrics. If this is significantly higher than what’s configured in
distributed.admin.tick.interval(default: 20ms), it highlights a blocked event loop, which in turn hampers timely task execution and network comms.- dask_worker_spill_bytes_total
Total size of spilled/unspilled data since the worker was started; in other words, cumulative disk I/O that is attributable to spill activity. This includes a
memory_readmeasure, which allows to derive cache hit ratio:cache hit ratio = memory_read / (memory_read + disk_read)
- dask_worker_spill_count_total
Total number of spilled/unspilled keys since the worker was started; in other words, cumulative disk accesses that are attributable to spill activity. This includes a
memory_readmeasure, which allows to derive cache hit ratio:cache hit ratio = memory_read / (memory_read + disk_read)
- dask_worker_spill_time_seconds_total
Total amount of time that was spent spilling/unspilling since the worker was started, broken down by activity: (de)serialize, (de)compress, (un)spill.
If the crick package is installed, the worker additionally exposes:
- dask_worker_tick_duration_median_seconds
Median tick duration at worker
- dask_worker_task_duration_median_seconds
Median task runtime at worker
- dask_worker_transfer_bandwidth_median_bytes
Bandwidth for transfer at worker