修改 linux thread 下单个进程能创建的线程数量的限制

在 linux thread 下单个进程能创建的最大线程数在 glibc 编译期就已经确定下来了，如果要加大进程能创建的线程数量，
需要重新编译 glibc，改变相关的限制。:-)，一般需要修改linuxthreads/internals.h 中的 STACK_SIZE 和 
linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h 文件中的 PTHREAD_THREADS_MAX 的定义。

下面的 patch 是个修改的例子：

diff -urN glibc-2.2.x/linuxthreads/descr.h glibc-2.2.x.new/linuxthreads/descr.h
--- glibc-2.2.x/linuxthreads/descr.h    Mon Feb 25 10:55:48 2002
+++ glibc-2.2.x.new/linuxthreads/descr.h        Wed Aug  7 14:38:58 2002
@@ -201,7 +201,7 @@
    THREAD_SELF implementation is used, this must be a power of two and
    a multiple of PAGE_SIZE.  */
 #ifndef STACK_SIZE
-#define STACK_SIZE  (2 * 1024 * 1024)
+#define STACK_SIZE  (64 * PAGE_SIZE)
 #endif

 /* Get some notion of the current stack.  Need not be exactly the top
diff -urN glibc-2.2.x/linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h glibc-2.2.x.new/linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h 
--- glibc-2.2.x/linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h   Tue Apr
+++ glibc-2.2.x.new/linuxthreads/sysdeps/unix/sysv/linux/bits/local_lim.h
@@ -64,7 +64,7 @@
 /* The number of threads per process.  */
 #define _POSIX_THREAD_THREADS_MAX      64
 /* This is the value this implementation supports.  */
-#define PTHREAD_THREADS_MAX    1024
+#define PTHREAD_THREADS_MAX    8192

 /* Maximum amount by which a process can descrease its asynchronous I/O
    priority level.  */