Documentation

Register metrics that record internal GHC runtime metrics, and fork a new thread to periodically update those metrics. Returns the ThreadId of the monitoring thread.

The following metrics will be registered:

• ghc_bytes_allocated_total: Total number of bytes allocated
• ghc_num_gcs_total: Number of garbage collections performed (any generation, major and minor)
• ghc_max_bytes_used_total: Maximum number of live bytes seen so far
• ghc_num_byte_usage_samples_total: Number of byte usage samples taken, or equivalently the number of major GCs performed.
• ghc_cumulative_bytes_used_total: Sum of all byte usage samples, can be used with numByteUsageSamples to calculate averages with arbitrary weighting (if you are sampling this record multiple times).
• ghc_bytes_copied_total: Number of bytes copied during GC
• ghc_current_bytes_used: Number of live bytes at the end of the last major GC
• ghc_current_bytes_slop: Current number of bytes lost to slop
• ghc_max_bytes_slop_total: Maximum number of bytes lost to slop at any one time so far
• ghc_peak_bytes_allocated_total: Maximum number of bytes allocated
• ghc_mutator_cpu_seconds_total: CPU time spent running mutator threads. This does not include any profiling overhead or initialization.
• ghc_mutator_wall_seconds_total: Wall clock time spent running mutator threads. This does not include initialization.
• ghc_gc_cpu_seconds_total: CPU time spent running GC
• ghc_gc_wall_seconds_total: Wall clock time spent running GC
• ghc_cpu_seconds_total: Total CPU time elapsed since program start
• ghc_wall_seconds_total: Total wall clock time elapsed since start
• ghc_par_bytes_copied_total: Number of bytes copied during GC, minus space held by mutable lists held by the capabilities. Can be used with parMaxBytesCopied to determine how well parallel GC utilized all cores.
• ghc_par_max_bytes_copied_total: Sum of number of bytes copied each GC by the most active GC thread each GC. The ratio of parTotBytesCopied divided by parMaxBytesCopied approaches 1 for a maximally sequential run and approaches the number of threads (set by the RTS flag -N) for a maximally parallel run.
• ghc_prometheus_collection_time_seconds: Amount of time spent by the Prometheus library collecting GHC statistics
• ghc_prometheus_record_time_seconds: Amount of time spent by the Prometheus library recording GHC statistics