Shell命令使用管道时速度较慢，使用中间文件时速度较快

19

有没有人了解使用中间文件或使用管道时处理时间的巨大差异？我正在使用标准的工具在新鲜的debian squeeze服务器上将tiff转换为pdf。执行此操作的标准方法是先转换为ps。

不带管道：

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

带管：

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

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

在最后一条命令期间，gs进程始终处于100％的状态。

更新：
这是ps生成的strace输出：

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

这是管道版本的strace输出：当将输出管道传输到ps2pdf13中时，PS生成似乎要慢得多。 

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 
— 计划
source
这些是大文件吗？
— 哈立德
不，一点也不：tiff文件为1.8MB。
— 计划
2
@plang：您是否尝试strace过gs流程？也许当使用中间文件时，它正在以更大的块处理文件，或者发生类似的事情……
— Janne Pikkarainen 2012年
您可以提供特定版本的Ghostscript吗？gs -v
— ewwhite
1
这里是TIFF：sendspace.com/file/vqoxbs
— plang

Answers:

17

编辑：我在您的环境中用您的源文件运行了此文件，并得到以下结果：

[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

我添加了pv命令以查看发生了什么。这是发生了什么：

[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 MB的Postscript输出通过管道传递给ps2pdf13命令！@janneb是正确的，因为这是一个缓冲/管道问题。我尝试利用该unbuffer命令，但Ghostscript不喜欢伪终端。

有什么原因不能使用该tiff2pdf命令？

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

real    0m0.242s
user    0m0.176s
sys     0m0.064s
— 怀特
source
我可以看到一个区别，但是与我的1.8MB测试文件相比，它的重要性不那么重要。
— 计划
1
嗨，我想您找到了问题。谢谢！我不知道tiff2pdf存在。它的运行速度非常快，但是存在一个问题：与tiff2ps / ps2pdf13的356K相比，输出为26 MB大。
— 计划
1
使用jpeg压缩（384K）：tiff2pdf -j -o test.pdf test.tif或ZIP压缩（1.6M）：tiff2pdf -z -o test3.pdf test.tif
— ewwhite 2012年
1
带有“ -j”选项的tiff2pdf可纠正大小问题。
— plang 2012年
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