GHC.Stats

This module provides access to internal garbage collection and memory usage statistics. These statistics are not available unless a program is run with the -T RTS flag.

This module is GHC-only and should not be considered portable.

Since: 4.5.0.0

Runtime statistics

data RTSStats

Statistics about runtime activity since the start of the program. This is a mirror of the C struct RTSStats in RtsAPI.h

Since: 4.10.0.0

Constructors

RTSStats

Fields

• gcs :: Word32

  Total number of GCs

• major_gcs :: Word32

  Total number of major (oldest generation) GCs

• allocated_bytes :: Word64

  Total bytes allocated

• max_live_bytes :: Word64

  Maximum live data (including large objects + compact regions) in the heap. Updated after a major GC.

• max_large_objects_bytes :: Word64

  Maximum live data in large objects

• max_compact_bytes :: Word64

  Maximum live data in compact regions

• max_slop_bytes :: Word64

  Maximum slop

• max_mem_in_use_bytes :: Word64

  Maximum memory in use by the RTS

• cumulative_live_bytes :: Word64

  Sum of live bytes across all major GCs. Divided by major_gcs gives the average live data over the lifetime of the program.

• copied_bytes :: Word64

  Sum of copied_bytes across all GCs

• par_copied_bytes :: Word64

  Sum of copied_bytes across all parallel GCs

• cumulative_par_max_copied_bytes :: Word64

  Sum of par_max_copied_bytes across all parallel GCs. Deprecated.

• cumulative_par_balanced_copied_bytes :: Word64

  Sum of par_balanced_copied bytes across all parallel GCs

• init_cpu_ns :: RtsTime

  Total CPU time used by the init phase @since 4.12.0.0

• init_elapsed_ns :: RtsTime

  Total elapsed time used by the init phase @since 4.12.0.0

• mutator_cpu_ns :: RtsTime

  Total CPU time used by the mutator

• mutator_elapsed_ns :: RtsTime

  Total elapsed time used by the mutator

• gc_cpu_ns :: RtsTime

  Total CPU time used by the GC

• gc_elapsed_ns :: RtsTime

  Total elapsed time used by the GC

• cpu_ns :: RtsTime

  Total CPU time (at the previous GC)

• elapsed_ns :: RtsTime

  Total elapsed time (at the previous GC)

• nonmoving_gc_sync_cpu_ns :: RtsTime

  The CPU time used during the post-mark pause phase of the concurrent nonmoving GC.

• nonmoving_gc_sync_elapsed_ns :: RtsTime

  The time elapsed during the post-mark pause phase of the concurrent nonmoving GC.

• nonmoving_gc_sync_max_elapsed_ns :: RtsTime

  The maximum time elapsed during the post-mark pause phase of the concurrent nonmoving GC.

• nonmoving_gc_cpu_ns :: RtsTime

  The CPU time used during the post-mark pause phase of the concurrent nonmoving GC.

• nonmoving_gc_elapsed_ns :: RtsTime

  The time elapsed during the post-mark pause phase of the concurrent nonmoving GC.

• nonmoving_gc_max_elapsed_ns :: RtsTime

  The maximum time elapsed during the post-mark pause phase of the concurrent nonmoving GC.

• gc :: GCDetails

  Details about the most recent GC

Instances

Read RTSStats

Since: 4.10.0.0

Defined in GHC.Stats

Methods

readsPrec :: Int -> ReadS RTSStats

readList :: ReadS [RTSStats]

readPrec :: ReadPrec RTSStats

readListPrec :: ReadPrec [RTSStats]

Show RTSStats

Since: 4.10.0.0

Defined in GHC.Stats

Methods

showsPrec :: Int -> RTSStats -> ShowS

show :: RTSStats -> String

showList :: [RTSStats] -> ShowS

data GCDetails

Statistics about a single GC. This is a mirror of the C struct GCDetails in RtsAPI.h, with the field prefixed with gc_ to avoid collisions with RTSStats.

Constructors

GCDetails

Fields

• gcdetails_gen :: Word32

  The generation number of this GC

• gcdetails_threads :: Word32

  Number of threads used in this GC

• gcdetails_allocated_bytes :: Word64

  Number of bytes allocated since the previous GC

• gcdetails_live_bytes :: Word64

  Total amount of live data in the heap (incliudes large + compact data). Updated after every GC. Data in uncollected generations (in minor GCs) are considered live.

• gcdetails_large_objects_bytes :: Word64

  Total amount of live data in large objects

• gcdetails_compact_bytes :: Word64

  Total amount of live data in compact regions

• gcdetails_slop_bytes :: Word64

  Total amount of slop (wasted memory)

• gcdetails_mem_in_use_bytes :: Word64

  Total amount of memory in use by the RTS

• gcdetails_copied_bytes :: Word64

  Total amount of data copied during this GC

• gcdetails_par_max_copied_bytes :: Word64

  In parallel GC, the max amount of data copied by any one thread. Deprecated.

• gcdetails_par_balanced_copied_bytes :: Word64

  In parallel GC, the amount of balanced data copied by all threads

• gcdetails_sync_elapsed_ns :: RtsTime

  The time elapsed during synchronisation before GC

• gcdetails_cpu_ns :: RtsTime

  The CPU time used during GC itself

• gcdetails_elapsed_ns :: RtsTime

  The time elapsed during GC itself

• gcdetails_nonmoving_gc_sync_cpu_ns :: RtsTime

  The CPU time used during the post-mark pause phase of the concurrent nonmoving GC.

• gcdetails_nonmoving_gc_sync_elapsed_ns :: RtsTime

  The time elapsed during the post-mark pause phase of the concurrent nonmoving GC.

Instances

Read GCDetails

Since: 4.10.0.0

Defined in GHC.Stats

Methods

readsPrec :: Int -> ReadS GCDetails

readList :: ReadS [GCDetails]

readPrec :: ReadPrec GCDetails

readListPrec :: ReadPrec [GCDetails]

Show GCDetails

Since: 4.10.0.0

Defined in GHC.Stats

Methods

showsPrec :: Int -> GCDetails -> ShowS

show :: GCDetails -> String

showList :: [GCDetails] -> ShowS

type RtsTime = Int64

Time values from the RTS, using a fixed resolution of nanoseconds.

getRTSStats :: IO RTSStats

Get current runtime system statistics.

Since: 4.10.0.0

getRTSStatsEnabled :: IO Bool

Returns whether GC stats have been enabled (with +RTS -T, for example).

Since: 4.10.0.0