Commande shell lente lors de l'utilisation de pipe, rapide avec fichier intermédiaire

19

Quelqu'un comprend-il cette énorme différence de temps de traitement, lors de l'utilisation d'un fichier intermédiaire ou lors de l'utilisation d'un canal? Je convertis tiff en pdf en utilisant des outils standard sur un nouveau serveur Debian Squeeze. Une manière standard de procéder consiste à convertir d'abord en ps.

Sans tuyau:

root@web5:~# time tiff2ps test.tif > test.ps

real    0m0.860s
user    0m0.744s
sys 0m0.112s

root@web5:~# time ps2pdf13 -sPAPERSIZE=a4 test.ps > test.pdf

real    0m0.667s
user    0m0.612s
sys 0m0.060s

Avec tuyau:

root@web5:~# time tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test.pdf

real    1m6.098s
user    0m15.861s
sys 0m50.9

Lors de la dernière commande, le processus gs est à 100% tout le temps.

Mise à jour :
Voici une sortie strace pour la génération ps:

root@web5:~# strace tiff2ps test.tif > test.ps
execve("/usr/bin/tiff2ps", ["tiff2ps", "test.tif"], [/* 28 vars */]) = 0
brk(0)                                  = 0x1395000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1937000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21735, ...}) = 0
mmap(NULL, 21735, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fb5a1931000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libtiff.so.4", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\200\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=405128, ...}) = 0
mmap(NULL, 2501416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a14b9000
mprotect(0x7fb5a151a000, 2093056, PROT_NONE) = 0
mmap(0x7fb5a1719000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x60000) = 0x7fb5a1719000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libjpeg.so.62", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3408\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=145048, ...}) = 0
mmap(NULL, 2240080, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a1296000
mprotect(0x7fb5a12b9000, 2093056, PROT_NONE) = 0
mmap(0x7fb5a14b8000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7fb5a14b8000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libz.so.1", O_RDONLY)    = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260\"\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=93936, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1930000
mmap(NULL, 2188976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a107f000
mprotect(0x7fb5a1096000, 2093056, PROT_NONE) = 0
mmap(0x7fb5a1295000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7fb5a1295000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libm.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360>\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=530736, ...}) = 0
mmap(NULL, 2625768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a0dfd000
mprotect(0x7fb5a0e7d000, 2097152, PROT_NONE) = 0
mmap(0x7fb5a107d000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7fb5a107d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0
mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a0a9b000
mprotect(0x7fb5a0bf4000, 2093056, PROT_NONE) = 0
mmap(0x7fb5a0df3000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7fb5a0df3000
mmap(0x7fb5a0df8000, 18504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb5a0df8000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192f000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192e000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192d000
arch_prctl(ARCH_SET_FS, 0x7fb5a192e700) = 0
mprotect(0x7fb5a0df3000, 16384, PROT_READ) = 0
mprotect(0x7fb5a107d000, 4096, PROT_READ) = 0
mprotect(0x7fb5a1939000, 4096, PROT_READ) = 0
munmap(0x7fb5a1931000, 21735)           = 0
open("test.tif", O_RDONLY)              = 3
brk(0)                                  = 0x1395000
brk(0x13b6000)                          = 0x13b6000
read(3, "II*\0\10\0\0\0", 8)            = 8
fstat(3, {st_mode=S_IFREG|0644, st_size=1825656, ...}) = 0
mmap(NULL, 1825656, PROT_READ, MAP_SHARED, 3, 0) = 0x7fb5a176f000
open("/proc/meminfo", O_RDONLY)         = 4
fstat(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1936000
read(4, "MemTotal:        2090844 kB\nMemF"..., 1024) = 1024
close(4)                                = 0
munmap(0x7fb5a1936000, 4096)            = 0
write(2, "TIFFReadDirectory: ", 19TIFFReadDirectory: )     = 19
write(2, "Warning, ", 9Warning, )                = 9
write(2, "test.tif: wrong data type 7 for "..., 59test.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored) = 59
write(2, ".\n", 2.
)                      = 2
gettimeofday({1334836895, 374666}, NULL) = 0
fstat(1, {st_mode=S_IFREG|0664, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1936000
open("/etc/localtime", O_RDONLY)        = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0
fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1935000
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0\0\0\0"..., 4096) = 1892
lseek(4, -1217, SEEK_CUR)               = 675
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\6\0\0\0\6\0\0\0\0"..., 4096) = 1217
close(4)                                = 0
munmap(0x7fb5a1935000, 4096)            = 0
write(1, "%!PS-Adobe-3.0 EPSF-3.0\n%%Creato"..., 4096) = 4096
write(1, "fffffffffffffffffffffffffffff\nff"..., 4096) = 4096
write(1, "ffffffffffffffffffff\nfffffffffff"..., 4096) = 4096
write(1, "fffffffffff\nffffffffffffffffffff"..., 4096) = 4096
write(1, "ff\nfffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffff\nfffffff"..., 4096) = 4096

Voici une sortie strace pour la version canalisée: la génération PS semble être beaucoup plus lente lorsque la sortie est canalisée dans ps2pdf13. 

root@web5:~# strace tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test.pdf
execve("/usr/bin/tiff2ps", ["tiff2ps", "test.tif"], [/* 28 vars */]) = 0
brk(0)                                  = 0x1b97000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb1000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21735, ...}) = 0
mmap(NULL, 21735, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9208bab000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libtiff.so.4", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\200\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=405128, ...}) = 0
mmap(NULL, 2501416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208733000
mprotect(0x7f9208794000, 2093056, PROT_NONE) = 0
mmap(0x7f9208993000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x60000) = 0x7f9208993000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libjpeg.so.62", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3408\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=145048, ...}) = 0
mmap(NULL, 2240080, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208510000
mprotect(0x7f9208533000, 2093056, PROT_NONE) = 0
mmap(0x7f9208732000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7f9208732000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libz.so.1", O_RDONLY)    = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260\"\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=93936, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208baa000
mmap(NULL, 2188976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f92082f9000
mprotect(0x7f9208310000, 2093056, PROT_NONE) = 0
mmap(0x7f920850f000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7f920850f000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libm.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360>\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=530736, ...}) = 0
mmap(NULL, 2625768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208077000
mprotect(0x7f92080f7000, 2097152, PROT_NONE) = 0
mmap(0x7f92082f7000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7f92082f7000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0
mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9207d15000
mprotect(0x7f9207e6e000, 2093056, PROT_NONE) = 0
mmap(0x7f920806d000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7f920806d000
mmap(0x7f9208072000, 18504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9208072000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba9000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba8000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba7000
arch_prctl(ARCH_SET_FS, 0x7f9208ba8700) = 0
mprotect(0x7f920806d000, 16384, PROT_READ) = 0
mprotect(0x7f92082f7000, 4096, PROT_READ) = 0
mprotect(0x7f9208bb3000, 4096, PROT_READ) = 0
munmap(0x7f9208bab000, 21735)           = 0
open("test.tif", O_RDONLY)              = 3
brk(0)                                  = 0x1b97000
brk(0x1bb8000)                          = 0x1bb8000
read(3, "II*\0\10\0\0\0", 8)            = 8
fstat(3, {st_mode=S_IFREG|0644, st_size=1825656, ...}) = 0
mmap(NULL, 1825656, PROT_READ, MAP_SHARED, 3, 0) = 0x7f92089e9000
open("/proc/meminfo", O_RDONLY)         = 4
fstat(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb0000
read(4, "MemTotal:        2090844 kB\nMemF"..., 1024) = 1024
close(4)                                = 0
munmap(0x7f9208bb0000, 4096)            = 0
write(2, "TIFFReadDirectory: ", 19TIFFReadDirectory: )     = 19
write(2, "Warning, ", 9Warning, )                = 9
write(2, "test.tif: wrong data type 7 for "..., 59test.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored) = 59
write(2, ".\n", 2.
)                      = 2
gettimeofday({1334836513, 114140}, NULL) = 0
fstat(1, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb0000
open("/etc/localtime", O_RDONLY)        = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0
fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208baf000
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0\0\0\0"..., 4096) = 1892
lseek(4, -1217, SEEK_CUR)               = 675
read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\6\0\0\0\6\0\0\0\0"..., 4096) = 1217
close(4)                                = 0
munmap(0x7f9208baf000, 4096)            = 0
write(1, "%!PS-Adobe-3.0 EPSF-3.0\n%%Creato"..., 4096) = 4096
write(1, "fffffffffffffffffffffffffffff\nff"..., 4096) = 4096
write(1, "ffffffffffffffffffff\nfffffffffff"..., 4096) = 4096
write(1, "fffffffffff\nffffffffffffffffffff"..., 4096) = 4096
write(1, "ff\nfffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096
...etc...
linux  bash  scripting  shell-scripting  pipe 
— plang
source
S'agit-il de gros fichiers?
— Khaled
Non, pas du tout: 1,8 Mo pour le fichier tiff.
— plang
2
@plang: Avez-vous essayé stracele processus gs? Peut-être qu'il traite le fichier en plus gros morceaux lors de l'utilisation du fichier intermédiaire, ou quelque chose de similaire se produit ...
— Janne Pikkarainen
Pouvez-vous fournir la version spécifique de Ghostscript? gs -v
— ewwhite
1
Voici le tiff: sendpace.com/file/vqoxbs
— plang

Réponses:

17

Edit: j'ai exécuté cela avec votre fichier source dans mon environnement et j'ai les résultats suivants:

[root@xt ~]# time tiff2ps test.tif > test.ps
real    0m0.795s
user    0m0.659s
sys     0m0.135s

[root@xt ~]# time ps2pdf13 -sPAPERSIZE=a4 test.ps > test.pdf
real    0m0.592s
user    0m0.513s
sys     0m0.075s

[root@xt ~]# time tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test2.pdf
real    0m13.110s
user    0m4.601s
sys     0m7.260s

J'ai ajouté la pvcommande pour voir ce qui se passait. Voici ce qui s'est passé:

[root@xt ~]# time tiff2ps test.tif | pv | ps2pdf13 -sPAPERSIZE=a4 - > test2.pdf
50.5MB 0:00:12 [4.05MB/s] [                      <=>                                                               ]

real    0m13.934s
user    0m4.751s
sys     0m8.261s

50 mégaoctets de sortie Postscript étant canalisés vers la ps2pdf13commande! @janneb avait raison en ce qu'il s'agit d'un problème de mise en mémoire tampon / pipe. J'ai essayé de tirer parti de la unbuffercommande , mais Ghostscript n'aime pas le pseudoterminal.

Y a-t-il une raison pour laquelle vous ne pouvez pas utiliser la tiff2pdfcommande?

[root@xt ~]# time tiff2pdf -o test2.pdf test.tif

real    0m0.242s
user    0m0.176s
sys     0m0.064s
— ewwhite
source
Il y a une différence que je peux voir, mais moins importante qu'avec mon fichier de test de 1,8 Mo.
— plang
1
Salut, je pense que vous avez trouvé le problème. Merci! Je ne savais pas que tiff2pdf existait. Cela fonctionne, très rapidement, mais il y a un problème: la sortie est de 26 Mo, comparée à 356K avec tiff2ps / ps2pdf13.
— plang
1
Exécutez-le avec une compression jpeg (384K): tiff2pdf -j -o test.pdf test.tifou une compression ZIP (1.6M):tiff2pdf -z -o test3.pdf test.tif
— ewwhite
1
tiff2pdf avec les options "-j" corrige le problème de taille.
— plang
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