Safe Haskell	Trustworthy
Language	Haskell2010

GHC.Stats

Contents

Runtime statistics

Description

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: base-4.5.0.0

Synopsis

data RTSStats = RTSStats {
- gcs :: Word32
- major_gcs :: Word32
- allocated_bytes :: Word64
- max_live_bytes :: Word64
- max_large_objects_bytes :: Word64
- max_compact_bytes :: Word64
- max_slop_bytes :: Word64
- max_mem_in_use_bytes :: Word64
- cumulative_live_bytes :: Word64
- copied_bytes :: Word64
- par_copied_bytes :: Word64
- cumulative_par_max_copied_bytes :: Word64
- cumulative_par_balanced_copied_bytes :: Word64
- init_cpu_ns :: RtsTime
- init_elapsed_ns :: RtsTime
- mutator_cpu_ns :: RtsTime
- mutator_elapsed_ns :: RtsTime
- gc_cpu_ns :: RtsTime
- gc_elapsed_ns :: RtsTime
- cpu_ns :: RtsTime
- elapsed_ns :: RtsTime
- gc :: GCDetails
}
data GCDetails = GCDetails {
}
type RtsTime = Int64
getRTSStats :: IO RTSStats
getRTSStatsEnabled :: IO Bool

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: base-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)
gc :: GCDetails
Details about the most recent GC

Instances

Read RTSStats #	Since: base-4.10.0.0
Instance details Defined in GHC.Stats Methods readsPrec :: Int -> ReadS RTSStats # readList :: ReadS [RTSStats] # readPrec :: ReadPrec RTSStats # readListPrec :: ReadPrec [RTSStats] #
Show RTSStats #	Since: base-4.10.0.0
Instance details 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

Instances

Read GCDetails #	Since: base-4.10.0.0
Instance details Defined in GHC.Stats Methods readsPrec :: Int -> ReadS GCDetails # readList :: ReadS [GCDetails] # readPrec :: ReadPrec GCDetails # readListPrec :: ReadPrec [GCDetails] #
Show GCDetails #	Since: base-4.10.0.0
Instance details 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: base-4.10.0.0

getRTSStatsEnabled :: IO Bool #

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

Since: base-4.10.0.0