Debugging Libraries

These are miscallenous libraries useful for debugging running programs.

Heap debugging utilities

To use bindings from this module

(import :std/debug/heap)

memory-usage

(memory-usage)

Aggregates useful memory statistics.

Example:

> (memory-usage)
((gc-heap-size . 31101000)
 (gc-alloc . 35786424)
 (gc-live . 12172776)
 (gc-movable . 11480480)
 (gc-still . 692296))

heap-type-stats

(heap-type-stats) -> (values live-objects type-table)

Returns two values, the number of live objects and a table containing a count for each type of live object.

dump-heap-stats!

(dump-heap-stats! (port (current-error-port)))

Dumps the current live heap statistics to port.

Example:

> (dump-heap-stats!)
=== memory usage ===
gc-heap-size: 31118680
gc-alloc: 72143824
gc-live: 12403320
gc-movable: 11693344
gc-still: 709976
=== heap summary ===
objects: 185028
still: 73
refcounted: 1
=== heap type counts ===
pair 59812
gx#import-binding::t 26592
gx#module-import::t 23607
string 17595
symbol 16772
gx#syntax-quote::t 11961
gx#module-export::t 7968
procedure 7476
vector 6542
gx#module-binding::t 2065
gx#extern-binding::t 1551
gx#syntax-binding::t 523
gx#macro-expander::t 357
bignum 311
##type-6-F3F63A41-2974-4D41-8B24-1744E866741D 251
weak 226
##type-5 166
keyword 164
gx#import-set::t 126
foreign 111
promise 103
gx#export-set::t 81
gx#context-phi::t 62
gx#module-context::t 58
gx#private-feature-expander::t 58
gerbil.core#runtime-struct-exhibitor::t 49
gerbil.core#extended-stuct-info::t 49
std/generic/macros#primitive-type-info::t 36
gerbil.core#extended-class-info::t 27
gerbil.core#runtime-class-exhibitor::t 27
std/generic/macros#builtin-type-info::t 21
gx#expander-mark::t 21
##type-11-42fe9aac-e9c6-4227-893e-a0ad76f58932 19
gx#alias-binding::t 19
gx#rename-macro-expander::t 18
box 18
gx#expression-form::t 15
gerbil/runtime/eval#__core-special-form::t 13
gerbil/runtime/eval#__core-expression::t 12
gerbil.core#runtime-class-info::t 10
gx#core-macro::t 10
u8vector 9
gx#reserved-expander::t 8
gerbil#AST::t 8
gx#top-special-form::t 8
gx#feature-expander::t 7
u16vector 6
##type-11-6bd864f0-27ec-4639-8044-cf7c0135d716 6
gx#export-expander::t 5
gx#import-expander::t 5
##type-49-a1d146d0-78f6-437f-aa67-3b9b5bb333dc 4
s32vector 4
f64vector 4
gx#definition-form::t 4
##type-41-B1E5C9EE-B4F9-4D3C-AACD-FE12D696101F 4
gerbil/runtime/eval#__core-form::t 4
gx#prelude-context::t 3
frame 2
##type-2-EACE4200-EB43-4891-852A-03C7B5D385E4 2
gx#import-export-expander::t 2
gx#module-special-form::t 2
unknown 2
gx#top-binding::t 2
continuation 2
gx#special-form::t 2
##type-7-cd5f5bad-f96f-438d-8d63-ff887b7b39de 2
##type-15-713f0ba8-1d76-4a68-8dfa-eaebd4aef1e3 2
gerbil/runtime/eval#__context::t 2
std/generic/dispatch#generic-table::t 1
std/generic/dispatch#generic::t 1
std/generic/macros#generic-info::t 1
##type-34-d05e0aa7-e235-441d-aa41-c1ac02065460 1
flonum 1
std/interface#interface-info::t 1
std/interface#interface-descriptor::t 1
gx#top-context::t 1
##type-8-1b002758-f900-4e96-be5e-fa407e331fc0 1
tmp/benchmark/interface/interface-lib#Operation::t 1
std/iter#:iter-end::t 1
tmp/benchmark/interface/interface-lib#LinearAccumulator::t 1
gx#root-context::t 1
##type-21-A6899D11-290C-42A6-B47A-57C6B908698F 1
##type-17-D7D5784C-16DC-4453-8832-CC05A6FE9353 1

walk-heap!

(walk-heap! walk: (walk #f) root: (root #f)) -> hash-table

Walks the heap, optionally starting from the specified root object and optionally using walk as the function for walking container objects.

Returns a table of all visited objects.

count-still

(count-still) -> (values still refcounted)

Returns two values: the number of still objects and how many of them are reference counted in the heap.

still-objects

(still-objects ...)

Counts the still objects in the heap.

still-objects/refcount

(still-objects/refcount ...)

Counts the reference counted objects in the heap.

Memory leak debugging utilities

To use bindings from this module

(import :std/debug/memleak)

heap-summary

(heap-summary)

Returns a differentiable heap summary.

heap-summary-delta

(heap-summary-delta old new)

Differentiates two heap summaries.

dump-heap-summary!

(dump-heap-summary! summary (port (current-error-port)))

Dumps a heap summary to port.

Example:

> (dump-heap-summary! (heap-summary))
==================================
timestamp: 1696260626.4030066
=== memory usage ===
gc-heap-size: 32177600
gc-live: 12572848
gc-movable: 11852528
gc-still: 720320
=== heap summary ===
objects: 187230
still: 74
refcounted: 1
=== heap type counts ===
pair: 60419
gx#import-binding::t: 27122
gx#module-import::t: 24133
string: 17807
symbol: 16977
gx#syntax-quote::t: 12013
gx#module-export::t: 7972
procedure: 7490
vector: 6567
gx#module-binding::t: 2078
gx#extern-binding::t: 1551
gx#syntax-binding::t: 524
gx#macro-expander::t: 357
bignum: 311
##type-6-F3F63A41-2974-4D41-8B24-1744E866741D: 252
weak: 227
keyword: 167
##type-5: 166
gx#import-set::t: 129
foreign: 112
promise: 104
gx#export-set::t: 81
gx#context-phi::t: 62
gx#module-context::t: 59
gx#private-feature-expander::t: 59
gerbil.core#runtime-struct-exhibitor::t: 49
gerbil.core#extended-stuct-info::t: 49
std/generic/macros#primitive-type-info::t: 36
gerbil.core#extended-class-info::t: 27
gerbil.core#runtime-class-exhibitor::t: 27
std/generic/macros#builtin-type-info::t: 21
gx#expander-mark::t: 21
##type-11-42fe9aac-e9c6-4227-893e-a0ad76f58932: 19
gx#alias-binding::t: 19
gx#rename-macro-expander::t: 18
box: 18
gx#expression-form::t: 15
gerbil/runtime/eval#__core-special-form::t: 13
gerbil/runtime/eval#__core-expression::t: 12
gerbil.core#runtime-class-info::t: 10
gx#core-macro::t: 10
u8vector: 9
gerbil#AST::t: 9
gx#reserved-expander::t: 8
gx#top-special-form::t: 8
gx#feature-expander::t: 7
u16vector: 6
##type-11-6bd864f0-27ec-4639-8044-cf7c0135d716: 6
gx#export-expander::t: 5
gx#import-expander::t: 5
##type-49-a1d146d0-78f6-437f-aa67-3b9b5bb333dc: 4
s32vector: 4
f64vector: 4
gx#definition-form::t: 4
##type-41-B1E5C9EE-B4F9-4D3C-AACD-FE12D696101F: 4
gerbil/runtime/eval#__core-form::t: 4
gx#prelude-context::t: 3
frame: 2
##type-2-EACE4200-EB43-4891-852A-03C7B5D385E4: 2
gx#import-export-expander::t: 2
gx#module-special-form::t: 2
unknown: 2
gx#top-binding::t: 2
continuation: 2
gx#special-form::t: 2
##type-7-cd5f5bad-f96f-438d-8d63-ff887b7b39de: 2
##type-15-713f0ba8-1d76-4a68-8dfa-eaebd4aef1e3: 2
gerbil/runtime/eval#__context::t: 2
std/generic/dispatch#generic::t: 1
std/generic/dispatch#generic-table::t: 1
std/generic/macros#generic-info::t: 1
##type-34-d05e0aa7-e235-441d-aa41-c1ac02065460: 1
flonum: 1
std/interface#interface-descriptor::t: 1
std/interface#interface-info::t: 1
gx#top-context::t: 1
##type-8-1b002758-f900-4e96-be5e-fa407e331fc0: 1
tmp/benchmark/interface/interface-lib#Operation::t: 1
std/iter#:iter-end::t: 1
tmp/benchmark/interface/interface-lib#LinearAccumulator::t: 1
gx#root-context::t: 1
##type-21-A6899D11-290C-42A6-B47A-57C6B908698F: 1
##type-17-D7D5784C-16DC-4453-8832-CC05A6FE9353: 1
=== frame counts ===
##with-no-result-expected-toplevel: 1
##kernel-handlers: 1
==================================

watch-heap!

(watch-heap! (port (current-error-port))
              delay: (initial-delay 60)
              period: (period (* 60 15))
              dump: (dump! dump-heap-summary!))

Watches the heap and dumps differential heap summaries with period, after initial-delay.

Thread debugging utilities

To use bindings from this module

(import :std/debug/threads)

dump-all-threads!

(dump-all-threads! (port (current-error-port))
                   (filter true))

Dumps the state of all threads that satisfy the filter procedure.

dump-all-threads/queue!

(dump-all-threads/queue! (port (current-error-port)))

Dumps all threads with a non empty message queue (mailbox).

dump-thread-group!

(dump-thread-group! (tg (current-thread-group))
                    (port (current-error-port))
                    (filter true))

Dumps all threads in the specified thread group tg, that satisfy the filter filter.

dump-thread-group!*

(dump-thread-group!* (tg (current-thread-group))
                          (port (current-error-port))
                          (filter true))

Like dump-thread-group!, but also recursively dumps all child thread groups.

dump-thread!

(dump-thread! thread (port (current-error-port)))

Dumps the state of a thread, including the size of its message queue and stack trace.

dump-thread-stack-trace!

(dump-thread-stack-trace! thread (port (current-error-port)))

Dumps a thread's stack trace.

thread-queue-length

(thread-queue-length thread)

Returns the current length of a thread's message queue.

thread-queue-empty?

(thread-queue-empty? thread)

Returns true if the thread's message queue is empty.

To use bindings from this module

(import :std/debug/DBG)

DBG

(DBG tag expr1 ... exprN) => values-of-the-last-expression

If the tag doesn't evaluate to #f, print the tag, then on separate lines the source of each expression expr1 to exprN (as by write) followed by its single or multiple return values (as by prn). Finally, return the values of the last expression exprN.

You can easily wrap an expression in a DBG form so as to print its value, together with the values of other relevant expressions, when trying to figure out where and how evaluation is failing your expectations in some part of your code.

Example:

> (define-values (x y z) (values 1 2 3))
> (* 10 (DBG foo: x (values [(+ x y) z] #t) (+ x y z)))
foo
  x => 1
  (values (@list (+ x y) z) #t) => [3 3] #t
  (+ x y z) => 6
60

In the above example the tag foo and the indented lines are printed by DBG, whereas the 60 is the final value returned and printed by the REPL. Notice how the DBG form returns the value of the last expression, 6, that subsequently got multiplied by 10 as per regular evaluation, to result in the final 60.

DBG-helper

(DBG-helper tag dbg-exprs dbg-thunks expr thunk) => values of the thunk

This is the function that DBG expands into, taking as parameters the tag, a list dbg-exprs of all-but-the-last expressions (quoted), a list dbg-thunks of thunks for all-but-the-last expressions, then the last expression expr (quoted) and the thunk for it. Your code can conceivably expand to calls to DBG-helper with e.g. suitable wrappings to tweak what expressions are printed.