description.go

Documentation: runtime/metrics

     1  // Copyright 2020 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package metrics
     6  
     7  import "internal/godebugs"
     8  
     9  // Description describes a runtime metric.
    10  type Description struct {
    11  	// Name is the full name of the metric which includes the unit.
    12  	//
    13  	// The format of the metric may be described by the following regular expression.
    14  	//
    15  	// 	^(?P<name>/[^:]+):(?P<unit>[^:*/]+(?:[*/][^:*/]+)*)$
    16  	//
    17  	// The format splits the name into two components, separated by a colon: a path which always
    18  	// starts with a /, and a machine-parseable unit. The name may contain any valid Unicode
    19  	// codepoint in between / characters, but by convention will try to stick to lowercase
    20  	// characters and hyphens. An example of such a path might be "/memory/heap/free".
    21  	//
    22  	// The unit is by convention a series of lowercase English unit names (singular or plural)
    23  	// without prefixes delimited by '*' or '/'. The unit names may contain any valid Unicode
    24  	// codepoint that is not a delimiter.
    25  	// Examples of units might be "seconds", "bytes", "bytes/second", "cpu-seconds",
    26  	// "byte*cpu-seconds", and "bytes/second/second".
    27  	//
    28  	// For histograms, multiple units may apply. For instance, the units of the buckets and
    29  	// the count. By convention, for histograms, the units of the count are always "samples"
    30  	// with the type of sample evident by the metric's name, while the unit in the name
    31  	// specifies the buckets' unit.
    32  	//
    33  	// A complete name might look like "/memory/heap/free:bytes".
    34  	Name string
    35  
    36  	// Description is an English language sentence describing the metric.
    37  	Description string
    38  
    39  	// Kind is the kind of value for this metric.
    40  	//
    41  	// The purpose of this field is to allow users to filter out metrics whose values are
    42  	// types which their application may not understand.
    43  	Kind ValueKind
    44  
    45  	// Cumulative is whether or not the metric is cumulative. If a cumulative metric is just
    46  	// a single number, then it increases monotonically. If the metric is a distribution,
    47  	// then each bucket count increases monotonically.
    48  	//
    49  	// This flag thus indicates whether or not it's useful to compute a rate from this value.
    50  	Cumulative bool
    51  }
    52  
    53  // The English language descriptions below must be kept in sync with the
    54  // descriptions of each metric in doc.go by running 'go generate'.
    55  var allDesc = []Description{
    56  	{
    57  		Name:        "/cgo/go-to-c-calls:calls",
    58  		Description: "Count of calls made from Go to C by the current process.",
    59  		Kind:        KindUint64,
    60  		Cumulative:  true,
    61  	},
    62  	{
    63  		Name: "/cpu/classes/gc/mark/assist:cpu-seconds",
    64  		Description: "Estimated total CPU time goroutines spent performing GC tasks " +
    65  			"to assist the GC and prevent it from falling behind the application. " +
    66  			"This metric is an overestimate, and not directly comparable to " +
    67  			"system CPU time measurements. Compare only with other /cpu/classes " +
    68  			"metrics.",
    69  		Kind:       KindFloat64,
    70  		Cumulative: true,
    71  	},
    72  	{
    73  		Name: "/cpu/classes/gc/mark/dedicated:cpu-seconds",
    74  		Description: "Estimated total CPU time spent performing GC tasks on " +
    75  			"processors (as defined by GOMAXPROCS) dedicated to those tasks. " +
    76  			"This metric is an overestimate, and not directly comparable to " +
    77  			"system CPU time measurements. Compare only with other /cpu/classes " +
    78  			"metrics.",
    79  		Kind:       KindFloat64,
    80  		Cumulative: true,
    81  	},
    82  	{
    83  		Name: "/cpu/classes/gc/mark/idle:cpu-seconds",
    84  		Description: "Estimated total CPU time spent performing GC tasks on " +
    85  			"spare CPU resources that the Go scheduler could not otherwise find " +
    86  			"a use for. This should be subtracted from the total GC CPU time to " +
    87  			"obtain a measure of compulsory GC CPU time. " +
    88  			"This metric is an overestimate, and not directly comparable to " +
    89  			"system CPU time measurements. Compare only with other /cpu/classes " +
    90  			"metrics.",
    91  		Kind:       KindFloat64,
    92  		Cumulative: true,
    93  	},
    94  	{
    95  		Name: "/cpu/classes/gc/pause:cpu-seconds",
    96  		Description: "Estimated total CPU time spent with the application paused by " +
    97  			"the GC. Even if only one thread is running during the pause, this is " +
    98  			"computed as GOMAXPROCS times the pause latency because nothing else " +
    99  			"can be executing. This is the exact sum of samples in " +
   100  			"/sched/pauses/total/gc:seconds if each sample is multiplied by " +
   101  			"GOMAXPROCS at the time it is taken. This metric is an overestimate, " +
   102  			"and not directly comparable to system CPU time measurements. Compare " +
   103  			"only with other /cpu/classes metrics.",
   104  		Kind:       KindFloat64,
   105  		Cumulative: true,
   106  	},
   107  	{
   108  		Name: "/cpu/classes/gc/total:cpu-seconds",
   109  		Description: "Estimated total CPU time spent performing GC tasks. " +
   110  			"This metric is an overestimate, and not directly comparable to " +
   111  			"system CPU time measurements. Compare only with other /cpu/classes " +
   112  			"metrics. Sum of all metrics in /cpu/classes/gc.",
   113  		Kind:       KindFloat64,
   114  		Cumulative: true,
   115  	},
   116  	{
   117  		Name: "/cpu/classes/idle:cpu-seconds",
   118  		Description: "Estimated total available CPU time not spent executing any Go or Go runtime code. " +
   119  			"In other words, the part of /cpu/classes/total:cpu-seconds that was unused. " +
   120  			"This metric is an overestimate, and not directly comparable to " +
   121  			"system CPU time measurements. Compare only with other /cpu/classes " +
   122  			"metrics.",
   123  		Kind:       KindFloat64,
   124  		Cumulative: true,
   125  	},
   126  	{
   127  		Name: "/cpu/classes/scavenge/assist:cpu-seconds",
   128  		Description: "Estimated total CPU time spent returning unused memory to the " +
   129  			"underlying platform in response eagerly in response to memory pressure. " +
   130  			"This metric is an overestimate, and not directly comparable to " +
   131  			"system CPU time measurements. Compare only with other /cpu/classes " +
   132  			"metrics.",
   133  		Kind:       KindFloat64,
   134  		Cumulative: true,
   135  	},
   136  	{
   137  		Name: "/cpu/classes/scavenge/background:cpu-seconds",
   138  		Description: "Estimated total CPU time spent performing background tasks " +
   139  			"to return unused memory to the underlying platform. " +
   140  			"This metric is an overestimate, and not directly comparable to " +
   141  			"system CPU time measurements. Compare only with other /cpu/classes " +
   142  			"metrics.",
   143  		Kind:       KindFloat64,
   144  		Cumulative: true,
   145  	},
   146  	{
   147  		Name: "/cpu/classes/scavenge/total:cpu-seconds",
   148  		Description: "Estimated total CPU time spent performing tasks that return " +
   149  			"unused memory to the underlying platform. " +
   150  			"This metric is an overestimate, and not directly comparable to " +
   151  			"system CPU time measurements. Compare only with other /cpu/classes " +
   152  			"metrics. Sum of all metrics in /cpu/classes/scavenge.",
   153  		Kind:       KindFloat64,
   154  		Cumulative: true,
   155  	},
   156  	{
   157  		Name: "/cpu/classes/total:cpu-seconds",
   158  		Description: "Estimated total available CPU time for user Go code " +
   159  			"or the Go runtime, as defined by GOMAXPROCS. In other words, GOMAXPROCS " +
   160  			"integrated over the wall-clock duration this process has been executing for. " +
   161  			"This metric is an overestimate, and not directly comparable to " +
   162  			"system CPU time measurements. Compare only with other /cpu/classes " +
   163  			"metrics. Sum of all metrics in /cpu/classes.",
   164  		Kind:       KindFloat64,
   165  		Cumulative: true,
   166  	},
   167  	{
   168  		Name: "/cpu/classes/user:cpu-seconds",
   169  		Description: "Estimated total CPU time spent running user Go code. This may " +
   170  			"also include some small amount of time spent in the Go runtime. " +
   171  			"This metric is an overestimate, and not directly comparable to " +
   172  			"system CPU time measurements. Compare only with other /cpu/classes " +
   173  			"metrics.",
   174  		Kind:       KindFloat64,
   175  		Cumulative: true,
   176  	},
   177  	{
   178  		Name:        "/gc/cycles/automatic:gc-cycles",
   179  		Description: "Count of completed GC cycles generated by the Go runtime.",
   180  		Kind:        KindUint64,
   181  		Cumulative:  true,
   182  	},
   183  	{
   184  		Name:        "/gc/cycles/forced:gc-cycles",
   185  		Description: "Count of completed GC cycles forced by the application.",
   186  		Kind:        KindUint64,
   187  		Cumulative:  true,
   188  	},
   189  	{
   190  		Name:        "/gc/cycles/total:gc-cycles",
   191  		Description: "Count of all completed GC cycles.",
   192  		Kind:        KindUint64,
   193  		Cumulative:  true,
   194  	},
   195  	{
   196  		Name: "/gc/gogc:percent",
   197  		Description: "Heap size target percentage configured by the user, otherwise 100. This " +
   198  			"value is set by the GOGC environment variable, and the runtime/debug.SetGCPercent " +
   199  			"function.",
   200  		Kind: KindUint64,
   201  	},
   202  	{
   203  		Name: "/gc/gomemlimit:bytes",
   204  		Description: "Go runtime memory limit configured by the user, otherwise " +
   205  			"math.MaxInt64. This value is set by the GOMEMLIMIT environment variable, and " +
   206  			"the runtime/debug.SetMemoryLimit function.",
   207  		Kind: KindUint64,
   208  	},
   209  	{
   210  		Name: "/gc/heap/allocs-by-size:bytes",
   211  		Description: "Distribution of heap allocations by approximate size. " +
   212  			"Bucket counts increase monotonically. " +
   213  			"Note that this does not include tiny objects as defined by " +
   214  			"/gc/heap/tiny/allocs:objects, only tiny blocks.",
   215  		Kind:       KindFloat64Histogram,
   216  		Cumulative: true,
   217  	},
   218  	{
   219  		Name:        "/gc/heap/allocs:bytes",
   220  		Description: "Cumulative sum of memory allocated to the heap by the application.",
   221  		Kind:        KindUint64,
   222  		Cumulative:  true,
   223  	},
   224  	{
   225  		Name: "/gc/heap/allocs:objects",
   226  		Description: "Cumulative count of heap allocations triggered by the application. " +
   227  			"Note that this does not include tiny objects as defined by " +
   228  			"/gc/heap/tiny/allocs:objects, only tiny blocks.",
   229  		Kind:       KindUint64,
   230  		Cumulative: true,
   231  	},
   232  	{
   233  		Name: "/gc/heap/frees-by-size:bytes",
   234  		Description: "Distribution of freed heap allocations by approximate size. " +
   235  			"Bucket counts increase monotonically. " +
   236  			"Note that this does not include tiny objects as defined by " +
   237  			"/gc/heap/tiny/allocs:objects, only tiny blocks.",
   238  		Kind:       KindFloat64Histogram,
   239  		Cumulative: true,
   240  	},
   241  	{
   242  		Name:        "/gc/heap/frees:bytes",
   243  		Description: "Cumulative sum of heap memory freed by the garbage collector.",
   244  		Kind:        KindUint64,
   245  		Cumulative:  true,
   246  	},
   247  	{
   248  		Name: "/gc/heap/frees:objects",
   249  		Description: "Cumulative count of heap allocations whose storage was freed " +
   250  			"by the garbage collector. " +
   251  			"Note that this does not include tiny objects as defined by " +
   252  			"/gc/heap/tiny/allocs:objects, only tiny blocks.",
   253  		Kind:       KindUint64,
   254  		Cumulative: true,
   255  	},
   256  	{
   257  		Name:        "/gc/heap/goal:bytes",
   258  		Description: "Heap size target for the end of the GC cycle.",
   259  		Kind:        KindUint64,
   260  	},
   261  	{
   262  		Name:        "/gc/heap/live:bytes",
   263  		Description: "Heap memory occupied by live objects that were marked by the previous GC.",
   264  		Kind:        KindUint64,
   265  	},
   266  	{
   267  		Name:        "/gc/heap/objects:objects",
   268  		Description: "Number of objects, live or unswept, occupying heap memory.",
   269  		Kind:        KindUint64,
   270  	},
   271  	{
   272  		Name: "/gc/heap/tiny/allocs:objects",
   273  		Description: "Count of small allocations that are packed together into blocks. " +
   274  			"These allocations are counted separately from other allocations " +
   275  			"because each individual allocation is not tracked by the runtime, " +
   276  			"only their block. Each block is already accounted for in " +
   277  			"allocs-by-size and frees-by-size.",
   278  		Kind:       KindUint64,
   279  		Cumulative: true,
   280  	},
   281  	{
   282  		Name: "/gc/limiter/last-enabled:gc-cycle",
   283  		Description: "GC cycle the last time the GC CPU limiter was enabled. " +
   284  			"This metric is useful for diagnosing the root cause of an out-of-memory " +
   285  			"error, because the limiter trades memory for CPU time when the GC's CPU " +
   286  			"time gets too high. This is most likely to occur with use of SetMemoryLimit. " +
   287  			"The first GC cycle is cycle 1, so a value of 0 indicates that it was never enabled.",
   288  		Kind: KindUint64,
   289  	},
   290  	{
   291  		Name:        "/gc/pauses:seconds",
   292  		Description: "Deprecated. Prefer the identical /sched/pauses/total/gc:seconds.",
   293  		Kind:        KindFloat64Histogram,
   294  		Cumulative:  true,
   295  	},
   296  	{
   297  		Name:        "/gc/scan/globals:bytes",
   298  		Description: "The total amount of global variable space that is scannable.",
   299  		Kind:        KindUint64,
   300  	},
   301  	{
   302  		Name:        "/gc/scan/heap:bytes",
   303  		Description: "The total amount of heap space that is scannable.",
   304  		Kind:        KindUint64,
   305  	},
   306  	{
   307  		Name:        "/gc/scan/stack:bytes",
   308  		Description: "The number of bytes of stack that were scanned last GC cycle.",
   309  		Kind:        KindUint64,
   310  	},
   311  	{
   312  		Name:        "/gc/scan/total:bytes",
   313  		Description: "The total amount space that is scannable. Sum of all metrics in /gc/scan.",
   314  		Kind:        KindUint64,
   315  	},
   316  	{
   317  		Name:        "/gc/stack/starting-size:bytes",
   318  		Description: "The stack size of new goroutines.",
   319  		Kind:        KindUint64,
   320  		Cumulative:  false,
   321  	},
   322  	{
   323  		Name: "/memory/classes/heap/free:bytes",
   324  		Description: "Memory that is completely free and eligible to be returned to the underlying system, " +
   325  			"but has not been. This metric is the runtime's estimate of free address space that is backed by " +
   326  			"physical memory.",
   327  		Kind: KindUint64,
   328  	},
   329  	{
   330  		Name:        "/memory/classes/heap/objects:bytes",
   331  		Description: "Memory occupied by live objects and dead objects that have not yet been marked free by the garbage collector.",
   332  		Kind:        KindUint64,
   333  	},
   334  	{
   335  		Name: "/memory/classes/heap/released:bytes",
   336  		Description: "Memory that is completely free and has been returned to the underlying system. This " +
   337  			"metric is the runtime's estimate of free address space that is still mapped into the process, " +
   338  			"but is not backed by physical memory.",
   339  		Kind: KindUint64,
   340  	},
   341  	{
   342  		Name: "/memory/classes/heap/stacks:bytes",
   343  		Description: "Memory allocated from the heap that is reserved for stack space, whether or not it is currently in-use. " +
   344  			"Currently, this represents all stack memory for goroutines. It also includes all OS thread stacks in non-cgo programs. " +
   345  			"Note that stacks may be allocated differently in the future, and this may change.",
   346  		Kind: KindUint64,
   347  	},
   348  	{
   349  		Name:        "/memory/classes/heap/unused:bytes",
   350  		Description: "Memory that is reserved for heap objects but is not currently used to hold heap objects.",
   351  		Kind:        KindUint64,
   352  	},
   353  	{
   354  		Name:        "/memory/classes/metadata/mcache/free:bytes",
   355  		Description: "Memory that is reserved for runtime mcache structures, but not in-use.",
   356  		Kind:        KindUint64,
   357  	},
   358  	{
   359  		Name:        "/memory/classes/metadata/mcache/inuse:bytes",
   360  		Description: "Memory that is occupied by runtime mcache structures that are currently being used.",
   361  		Kind:        KindUint64,
   362  	},
   363  	{
   364  		Name:        "/memory/classes/metadata/mspan/free:bytes",
   365  		Description: "Memory that is reserved for runtime mspan structures, but not in-use.",
   366  		Kind:        KindUint64,
   367  	},
   368  	{
   369  		Name:        "/memory/classes/metadata/mspan/inuse:bytes",
   370  		Description: "Memory that is occupied by runtime mspan structures that are currently being used.",
   371  		Kind:        KindUint64,
   372  	},
   373  	{
   374  		Name:        "/memory/classes/metadata/other:bytes",
   375  		Description: "Memory that is reserved for or used to hold runtime metadata.",
   376  		Kind:        KindUint64,
   377  	},
   378  	{
   379  		Name: "/memory/classes/os-stacks:bytes",
   380  		Description: "Stack memory allocated by the underlying operating system. " +
   381  			"In non-cgo programs this metric is currently zero. This may change in the future." +
   382  			"In cgo programs this metric includes OS thread stacks allocated directly from the OS. " +
   383  			"Currently, this only accounts for one stack in c-shared and c-archive build modes, " +
   384  			"and other sources of stacks from the OS are not measured. This too may change in the future.",
   385  		Kind: KindUint64,
   386  	},
   387  	{
   388  		Name:        "/memory/classes/other:bytes",
   389  		Description: "Memory used by execution trace buffers, structures for debugging the runtime, finalizer and profiler specials, and more.",
   390  		Kind:        KindUint64,
   391  	},
   392  	{
   393  		Name:        "/memory/classes/profiling/buckets:bytes",
   394  		Description: "Memory that is used by the stack trace hash map used for profiling.",
   395  		Kind:        KindUint64,
   396  	},
   397  	{
   398  		Name:        "/memory/classes/total:bytes",
   399  		Description: "All memory mapped by the Go runtime into the current process as read-write. Note that this does not include memory mapped by code called via cgo or via the syscall package. Sum of all metrics in /memory/classes.",
   400  		Kind:        KindUint64,
   401  	},
   402  	{
   403  		Name:        "/sched/gomaxprocs:threads",
   404  		Description: "The current runtime.GOMAXPROCS setting, or the number of operating system threads that can execute user-level Go code simultaneously.",
   405  		Kind:        KindUint64,
   406  	},
   407  	{
   408  		Name:        "/sched/goroutines:goroutines",
   409  		Description: "Count of live goroutines.",
   410  		Kind:        KindUint64,
   411  	},
   412  	{
   413  		Name:        "/sched/latencies:seconds",
   414  		Description: "Distribution of the time goroutines have spent in the scheduler in a runnable state before actually running. Bucket counts increase monotonically.",
   415  		Kind:        KindFloat64Histogram,
   416  		Cumulative:  true,
   417  	},
   418  	{
   419  		Name:        "/sched/pauses/stopping/gc:seconds",
   420  		Description: "Distribution of individual GC-related stop-the-world stopping latencies. This is the time it takes from deciding to stop the world until all Ps are stopped. This is a subset of the total GC-related stop-the-world time (/sched/pauses/total/gc:seconds). During this time, some threads may be executing. Bucket counts increase monotonically.",
   421  		Kind:        KindFloat64Histogram,
   422  		Cumulative:  true,
   423  	},
   424  	{
   425  		Name:        "/sched/pauses/stopping/other:seconds",
   426  		Description: "Distribution of individual non-GC-related stop-the-world stopping latencies. This is the time it takes from deciding to stop the world until all Ps are stopped. This is a subset of the total non-GC-related stop-the-world time (/sched/pauses/total/other:seconds). During this time, some threads may be executing. Bucket counts increase monotonically.",
   427  		Kind:        KindFloat64Histogram,
   428  		Cumulative:  true,
   429  	},
   430  	{
   431  		Name:        "/sched/pauses/total/gc:seconds",
   432  		Description: "Distribution of individual GC-related stop-the-world pause latencies. This is the time from deciding to stop the world until the world is started again. Some of this time is spent getting all threads to stop (this is measured directly in /sched/pauses/stopping/gc:seconds), during which some threads may still be running. Bucket counts increase monotonically.",
   433  		Kind:        KindFloat64Histogram,
   434  		Cumulative:  true,
   435  	},
   436  	{
   437  		Name:        "/sched/pauses/total/other:seconds",
   438  		Description: "Distribution of individual non-GC-related stop-the-world pause latencies. This is the time from deciding to stop the world until the world is started again. Some of this time is spent getting all threads to stop (measured directly in /sched/pauses/stopping/other:seconds). Bucket counts increase monotonically.",
   439  		Kind:        KindFloat64Histogram,
   440  		Cumulative:  true,
   441  	},
   442  	{
   443  		Name:        "/sync/mutex/wait/total:seconds",
   444  		Description: "Approximate cumulative time goroutines have spent blocked on a sync.Mutex, sync.RWMutex, or runtime-internal lock. This metric is useful for identifying global changes in lock contention. Collect a mutex or block profile using the runtime/pprof package for more detailed contention data.",
   445  		Kind:        KindFloat64,
   446  		Cumulative:  true,
   447  	},
   448  }
   449  
   450  func init() {
   451  	// Insert all the non-default-reporting GODEBUGs into the table,
   452  	// preserving the overall sort order.
   453  	i := 0
   454  	for i < len(allDesc) && allDesc[i].Name < "/godebug/" {
   455  		i++
   456  	}
   457  	more := make([]Description, i, len(allDesc)+len(godebugs.All))
   458  	copy(more, allDesc)
   459  	for _, info := range godebugs.All {
   460  		if !info.Opaque {
   461  			more = append(more, Description{
   462  				Name: "/godebug/non-default-behavior/" + info.Name + ":events",
   463  				Description: "The number of non-default behaviors executed by the " +
   464  					info.Package + " package " + "due to a non-default " +
   465  					"GODEBUG=" + info.Name + "=... setting.",
   466  				Kind:       KindUint64,
   467  				Cumulative: true,
   468  			})
   469  		}
   470  	}
   471  	allDesc = append(more, allDesc[i:]...)
   472  }
   473  
   474  // All returns a slice of containing metric descriptions for all supported metrics.
   475  func All() []Description {
   476  	return allDesc
   477  }
   478
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