PHP垃圾收集器统计信息

export CFLAGS=-DGC_BENCH=1
./config.nice
make clean
make
make install

<?php
class Foo
{
    public $var = '3.1415962654';
}

for ( $i = 0; $i <= 1000000; $i++ )
{
    $a = new Foo;
    $a->self = $a;
}

echo memory_get_peak_usage(),"n";
?>

GC Statistics
-------------
Runs:               110
Collected:          2072204
Root buffer length: 0
Root buffer peak:   10000

      Possible            Remove from  Marked
        Root    Buffered     buffer     grey
      --------  --------  -----------  ------
ZVAL   7175487   1491291    1241690   3611871
ZOBJ  28506264   1527980     677581   1025731

我在这里预感,因为我没有证实这一点,但是,通过阅读你提供的GC链接上的文字,我不会觉得memory_get_peak_usage()应该返回基于使用DGC_BENCH编译PHP的附加信息旗.手册说它返回一个int,所以我怀疑它总是返回一个int.

然而它说的是：

When you run the above example code again with the newly built PHP
binary,you will see the following being shown after PHP has finished
execution:

这不是很清楚,但我的印象是,额外的GC细节将打印到stdout或stderr而不是返回到memory_get_peak_usage()或作为额外输出打印到PHP脚本.

尝试从命令行调用新构建的PHP可执行文件,并在脚本完成时查看是否将GC信息打印到控制台.

您可以尝试调用它：/ path / to / custom / php testfile.php

如果您将PHP作为Apache模块或FastCGI处理程序运行,我不确定输出此信息是否有意义所以我怀疑您可能只能通过从控制台调用脚本来查看它,但我可能完全错了.

更新：

我已经检查过以确保GC_BENCH编译标志仍处于活动状态,它是.

Zend公司/ zend.c

905 #if GC_BENCH
906     fprintf(stderr,"GC Statisticsn");
907     fprintf(stderr,"-------------n");
908     fprintf(stderr,"Runs:               %dn",GC_G(gc_runs));
909     fprintf(stderr,"Collected:          %dn",GC_G(collected));
910     fprintf(stderr,"Root buffer length: %dn",GC_G(root_buf_length));
911     fprintf(stderr,"Root buffer peak:   %dnn",GC_G(root_buf_peak));
912     fprintf(stderr,"      Possible            Remove from  Markedn");
913     fprintf(stderr,"        Root    Buffered     buffer     greyn");
914     fprintf(stderr,"      --------  --------  -----------  ------n");
915     fprintf(stderr,"ZVAL  %8d  %8d  %9d  %8dn",GC_G(zval_possible_root),GC_G(zval_buffered),GC_G(zval_remove_from_buffer),GC_G(zval_marked_grey));
916     fprintf(stderr,"ZOBJ  %8d  %8d  %9d  %8dn",GC_G(zobj_possible_root),GC_G(zobj_buffered),GC_G(zobj_remove_from_buffer),GC_G(zobj_marked_grey));
917 #endif

接下来,我为Apache2和CLI编译了PHP 5.3.9.在决定安装测试版之前,我从控制台运行了新的PHP CLI应用程序：

./sapi/cli/php -v

PHP 5.3.9 (cli) (built: Feb 22 2012 19:03:02) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0,Copyright (c) 1998-2012 Zend Technologies
GC Statistics
-------------
Runs:               0
Collected:          0
Root buffer length: 0
Root buffer peak:   7

      Possible            Remove from  Marked
        Root    Buffered     buffer     grey
      --------  --------  -----------  ------
ZVAL        15         7          7         0
ZOBJ         0         0          0         0

即使我没有调用PHP,它也有GC输出.接下来我grep了libphp5.so,看到它已经编译了GC Statistics位,所以我决定安装它并从Apache拨打电话.浏览器,error_log,access_log或任何其他日志文件中没有GC输出.

现在有趣的部分,我创建了一个test.php文件,它输出一个字符串并创建一个释放一些变量……

root@vm:/php539# php test.php
This is a test

root@vm:/php539# php < test.php
This is a test
GC Statistics
-------------
Runs:               0
Collected:          0
Root buffer length: 0
Root buffer peak:   7

      Possible            Remove from  Marked
        Root    Buffered     buffer     grey
      --------  --------  -----------  ------
ZVAL        16         7          7         0
ZOBJ         0         0          0         0

root@vm:php539#

结论：

使用GC_BENCH选项编译PHP时,从浏览器调用时,或使用-f选项解析PHP文件或传递要解析的文件名时,将无法访问基准信息.如果您以交互模式调用php,或者通过从stdin读取它来通过PHP执行脚本,您将获得基准信息.