Ludovic Courtès <l...@gnu.org> skribis:
> #104 0x00007fc5247f3a92 in scm_hash_fn_ref () from
> /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
> #105 0x00007fc524859715 in vm_regular_engine () from
> /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
> #106 0x00007fc52485cd6a in scm_call_n () from
> /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
> #107 0x00007fc5247e0da7 in scm_primitive_eval () from
> /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
>
>
> and with debugging symbols:
>
> #3 0x00007fc5247ddc23 in scm_equal_p
> (x=x@entry="/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0/bin/guile",
>
>
> y=y@entry="/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0/bin/guile")
> at eq.c:290
> #4 0x00007fc52484891b in scm_i_struct_equalp (s1="#<struct <derivation>>" =
> {...}, s2="#<struct <derivation>>" = {...}) at struct.c:693
> #5 0x00007fc52484891b in scm_i_struct_equalp (s1="#<struct
> <derivation-input>>" = {...}, s2="#<struct <derivation-input>>" = {...}) at
> struct.c:693
> #6 0x00007fc5247ddc82 in scm_equal_p (
> x=(#<struct <derivation-input> #<struct <derivation> (("out" . #<struct
> <derivation-output>
> "/gnu/store/jc5q4i55hrilibrmacs38skk3cpg2zyb-glibc-bootstrap-0" #f #f #f
> 3ade740>)) (#<struct <derivation-input> #<struct <derivation> (("out" .
> #<struct <derivation-output>
> "/gnu/store/nbi0mzk1dw37nnnahw9akn3bwzwi4gdk-module-import-compiled" #f #f #f
> 3ae6e00>)) (#<struct <derivation-input> #<struct <derivation> (("out" .
> #<struct <derivation-output>
> "/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0" #f #f #f
> 3af1b40>)) (#<struct <derivation-input> #<struct <derivation> (("out" .
> #<struct <derivation-output>
> "/gnu/store/dgncc5wmw8prxq09y71hqjc6g7rxqvvb-guile-2.0.9.tar.xz" sha256
> #vu8(183 87 205 70 191 19 236 172 131 251 142 149 95 181 0 150 172 45 23 187
> 97 12 168 235 129 111 41 48 42 0 168 70) #f 3af10c0>)) ()
> ("/gnu/store/7f1alh9qj2h0wwy2220npgnmw6pbrkwx-mirrors"
> "/gnu/store/vwyxp1dq4lb97n6b20w5cqxasy2dai79-content-addressed-mirrors")
> "i686-linux" "builtin:download" () (("content-addressed-mirrors" .
> "/gnu/store/vwyxp1dq4lb97n6b20w5cqxasy2dai79-content-addressed-mirrors")
> ("impureEnvVars" . "http_proxy https_proxy LC_ALL LC_MESSAGES LANG COLUMNS")
> ("mirrors" . "/gnu/store/7f1alh9qj2h0wwy2220npgnmw6pbrkwx-mirrors") ("out" .
> "/gnu/store/dgncc5wmw8prxq09y71hqjc6g7rxqvvb-guile-2.0.9.tar.xz")
> ("preferLocalBuild" . "1") ("url" .
> "(\"https://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\";
>
> \"http://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\";
>
> \"ftp://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\";
>
> \"http://www.fdn.fr/~lcourtes/software/guix/packages/i686-linux/20131110/guile-2.0.9.tar.xz\";
>
> \"http://flashner.co.il/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\";)"))
> "/gnu/store/jagg4l53ar1m4hsgqlpisw9i4rq2whzd-guile-2.0.9.tar.xz.drv"
> 3af14e0> ("out") 3af1780>)
> ("/gnu/store/d32948vi9bs5mmbnvlczqcgwwdqvygiw-build-bootstrap-guile.sh"
> "/gnu/store/mzfkrxd4w8vqrmyrx169wj8wyw7r8i37-bash") "i686-linux"
> "/gnu/store/mzfkrxd4w8 […]
>
> So this process is busy comparing deep structures, probably as a
> consequence of 5cf4b26d52bcea382d98fb4becce89be9ee37b55.
With some debugging, I found that the pathological behavior comes from
the memoization hash table of ‘derivation->bytevector’, specifically
after ‘invalidate-derivation-caches!’ has been called.
Namely, after ‘invalidate-derivation-caches!’ has been called, that hash
table has 24K buckets, including 72 buckets of size 6 or more. One
bucket has 18 entries, which are all alike:
#<derivation #f => /gnu/store/…-module-import-compiled 94283c0>
The ‘equal?’ calls come from those buckets, and each of them involves
traversing the whole <derivation> tree.
I’m looking for a workaround.
Ludo’.
PS: Below is some debugging code.
(use-modules (system foreign)
(ice-9 match))
;; typedef struct {
;; 0 scm_t_weak_entry **buckets; /* the data */
;; 8 scm_i_pthread_mutex_t lock; /* the lock */
;; 48 scm_t_weak_table_kind kind; /* what kind of table it is */
;; 56 unsigned long n_buckets; /* total number of buckets. */
;; 64 unsigned long n_items; /* number of items in table */
;; 72 unsigned long lower; /* when to shrink */
;; 80 unsigned long upper; /* when to grow */
;; 88 int size_index; /* index into hashtable_size */
;; 92 int min_size_index; /* minimum size_index */
;; 96 GC_word last_gc_no;
;; } scm_t_weak_table;
(define (weak-table-data table)
"Return an alist describing TABLE."
(unless (or (weak-key-hash-table? table)
(weak-value-hash-table? table))
(error "wrong type argument" table))
(let* ((address (object-address table))
(ptr (dereference-pointer
(make-pointer (+ address 8)))))
(match (parse-c-struct (make-pointer (+ (pointer-address ptr) 48))
(list int
unsigned-long unsigned-long
unsigned-long unsigned-long
int
int
unsigned-long))
((kind buckets items lower upper size-index min-size-index last-gc-no)
`((kind . ,kind) (items . ,items) (buckets . ,buckets)
(lower . ,lower) (upper . ,upper)
(size-index . ,size-index) (min-size-index . ,min-size-index)
(last-gc-no . ,last-gc-no))))))
;; typedef struct scm_t_hashtable {
;; unsigned long n_items; /* number of items in table */
;; unsigned long lower; /* when to shrink */
;; unsigned long upper; /* when to grow */
;; int size_index; /* index into hashtable_size */
;; int min_size_index; /* minimum size_index */
;; scm_t_hash_fn hash_fn; /* for rehashing after a GC. */
;; } scm_t_hashtable;
(define (hash-table-data table)
(unless (hash-table? table)
(error "wrong type argument" table))
(let* ((address (object-address table))
(ptr (dereference-pointer
(make-pointer (+ address (* 2 (sizeof '*)))))))
(match (parse-c-struct ptr
(list unsigned-long
unsigned-long unsigned-long
int
int))
((items lower upper size-index min-size-index)
`((items . ,items)
(lower . ,lower) (upper . ,upper)
(size-index . ,size-index) (min-size-index . ,min-size-index))))))
(define (hash-table-buckets table)
(unless (hash-table? table)
(error "wrong type argument" table))
(let* ((address (object-address table))
(ptr (dereference-pointer
(make-pointer (+ address (* 1 (sizeof '*)))))))
(pointer->scm ptr)))
(define (hash-table-bucket-sizes table)
(let ((buckets (hash-table-buckets table)))
(let loop ((index 0)
(result '()))
(if (< index (vector-length buckets))
(loop (+ 1 index)
(cons (length (vector-ref buckets index))
result))
(reverse result)))))
