很久没有更新博客了，说下系统环境：

uname -a
Linux REDHAT6 2.6.32-279.el6.x86_64 #1 SMP Wed Jun 13 18:24:36 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux

tomcat的java进程号1243

[root@REDHAT6 proc]# ps -eL|head -1PID   LWP TTY          TIME CMD
[root@REDHAT6 proc]# ps -eL|grep java1243  1243 pts/0    00:00:00 java1243  1244 pts/0    00:00:01 java1243  1245 pts/0    00:00:32 java1243  1246 pts/0    00:00:00 java1243  1247 pts/0    00:00:00 java1243  1248 pts/0    00:00:00 java1243  1249 pts/0    00:00:03 java1243  1250 pts/0    00:00:04 java1243  1251 pts/0    00:00:00 java1243  1252 pts/0    00:00:08 java1243  1253 pts/0    00:00:00 java1243  1259 pts/0    00:00:00 java

cd /proc

[root@REDHAT6 proc]# ls -d [0-9]*
1     1058  11    1158  12    1212  1395  16  2   23   25   27   293  31  35  381  40  44  52   692  729  733  9
10    1068  1111  1166  1207  1243  14    17  20  24   250  28   294  32  36  383  41  49  53   693  730  772
1014  1069  1128  1174  1209  1265  1462  18  21  242  251  29   3    33  37  39   42  5   6    7    731  8
1021  1097  1136  1189  1210  13    15    19  22  243  26   292  30   34  38  4    43  50  687  728  732  83我们会发现根本看不到1244,1245等pid，别急，[root@REDHAT6 proc]# ls 1244
attr       clear_refs       cwd      fdinfo    maps       mountstats  oom_score      root       smaps  status
autogroup  cmdline          environ  io        mem        net         oom_score_adj  sched      stack  syscall
auxv       coredump_filter  exe      limits    mountinfo  numa_maps   pagemap        schedstat  stat   task
cgroup     cpuset           fd       loginuid  mounts     oom_adj     personality    sessionid  statm  wchan
[root@REDHAT6 proc]# ll 1244/exe
lrwxrwxrwx 1 root root 0 11月  6 11:27 1244/exe -> /usr/local/jdk1.6.0_45/bin/java

看到了吧，虽然看不到1244，但是显示的内容其实就是1243的内容，本质上1244就是LWP进程号,linux的线程其实是LWP轻量级进程模拟出来的。

同时我们也可以理解，linux下最大进程数限制同时也对线程起了作用。如果要增大最大线程数，那就要增大最大进程数。

[root@REDHAT6 proc]# cat /etc/security/limits.d/90-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.*          soft    nproc     1024