经典的 UNIX编程书籍专门一章提到非线程安全函数（不可重入）。一般情况下，这个问题不好爆发，但是高并发程序引爆这个问题。

开发人员有时也会犯晕的。

例如：

void log(int level, char *file, int line, const char *function, char *fmt, ...)
{
 if (level>g_nLogLevel) return;

 char buffer[1024];
 time_t t;
 time(&t);
 struct tm *tm = ::localtime((const time_t*)&t);

其中的localtime是非线程安全

应该更改为 localtime_r

IBM RPM系统是WEB之上包装的非文本方式传输数据的系统。

为了开展性能测试，如何构造有效的网络包成为第一个坎。用YATT 嗅探器截获之前的通信包，保存为req.log。

 然后借用JAVA 里面HttpURLConnection 发送、接收数据，经测试通过。

import java.io.*;

import java.net.HttpURLConnection;

import java.util.Map;

import java.net.URL;

import java.util.zip.Deflater;

import java.util.zip.Inflater;

public class RpmSender {

      public static void main(String[] args) {

             try {

                    String log_dir = "D:\\rpm\\record2\\";

                    int  bufferlen =20480;

                     URL url = new                  URL("http://rpm.alibaba-inc.com:9080/webapp/IBMRPM/PMOServlet.wss");

                    //URL url = new URL("http://10.0.32.123:8081/IBMRPM/PMOServlet.wss");

                    OutputStream ōut = null;

                    InputStream is = null;

                    HttpURLConnection httpConnection = null;

                    for (int i = 1; i <= 16; i++) {

                           httpConnection = (HttpURLConnection) url

                                         .openConnection();

                           httpConnection.setRequestProperty("Content-Type",

                                         "application/octet-stream");

                           httpConnection.setRequestProperty("Accept", "text/html, */*");

                           httpConnection.setRequestProperty("Pragma", "no-cache");

                           httpConnection.setRequestProperty("Keep-Alive", "Y");

                           httpConnection.setRequestProperty("Accept-Encoding",

                                         "deflate, identity");

                           httpConnection.setRequestProperty("Zip", "D");

                           httpConnection.setRequestProperty("User-Agent", "IBMRPM");

                           httpConnection.setRequestProperty("Method", "POST");

                           httpConnection.setDoInput(true);

                           httpConnection.setDoOutput(true);

                           out = new BufferedOutputStream(httpConnection.getOutputStream());

                           String reqfile = i + "_req.log";

                           String resultfile = "result_" + i + "_reponse.log";

                           FileInputStream fstream = new FileInputStream(log_dir + reqfile);

                           String charset = "UTF-8"; //GBK,ISO-8859-1,GB2312,UTF-8

                           byte[] ōutput = new byte[bufferlen];

                           int readbyte = fstream.read(output);

                           System.out.println(readbyte);

                           //httpConnection.setRequestProperty("Content-Length",new

                           // Integer(readbyte).toString() );

                           out.write(output, 0, readbyte);

                           out.flush();

                           byte[] buffer = new byte[bufferlen * 3];

                           byte[] tmp = new byte[bufferlen];

                           int length;

                           int total_len = 0;

                           is = httpConnection.getInputStream();

                           while ((length = is.read(tmp)) > -1) {

                                  System.arraycopy(tmp, 0, buffer, total_len, length);

                                  total_len += length;

                           }

                           System.out.println(total_len);

                           Inflater decompresser = new Inflater();

                           decompresser.setInput(buffer, 0, total_len);

                           byte[] result = new byte[4096];

                           int resultLength = decompresser.inflate(result);

                           decompresser.end();

                           FileOutputStream fout = new FileOutputStream(log_dir

                                         + resultfile);

                           fout.write(result, 0, resultLength);

                           fout.close();

                           // Decode the bytes into a String

                           // String ōutputString = new String(result);

                           String ōutputString = new String(result, 0, resultLength,

                                         charset); //"UTF-8");

                           System.out.println(outputString);

                           out.close();

                           is.close();

                           httpConnection.disconnect();

                    }

             } catch (Exception e) {

                    e.printStackTrace();

             }

      }

}

WARN  internal.ParameterParserImpl - Upload failed
com.alibaba.service.upload.UploadException: Processing of multipart/form-data request failed. /tmp/upload_64f22eb1_113e12038a1__7fe6_00000000.tmp (No space left on device)
        at com.alibaba.service.upload.DefaultUploadService.parseRequest(DefaultUploadService.java:170)
        at com.alibaba.webx.request.context.parser.internal.ParameterParserImpl.parseUpload(P

df  -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             4.9G  2.2G  2.4G  48% /
/dev/sda1              99M   12M   83M  12% /boot
none                  2.0G     0  2.0G   0% /dev/shm
/dev/sda7             119G   45G   69G  40% /home
/dev/sda3             4.9G  3.9G  685M  86% /usr
/dev/sda5             2.9G  138M  2.6G   5% /var

[admin@b2bsearch211 logs]$ df  -i

Filesystem            Inodes   IUsed   IFree IUse% Mounted on

/dev/sda2             640000  640000       0  100% /

/dev/sda1              26104      38   26066    1% /boot

none                  218174       1  218173    1% /dev/shm

/dev/sda7            15826944  147888 15679056    1% /home

/dev/sda3             640000  147367  492633   24% /usr

/dev/sda5             384000    3210  380790    1% /var

  df -i 可以看到Inode节点已经满了。

  通过删除大量的小文件得以解决。

  更多参考

http://linux.chinaunix.net/bbs/viewthread.php?tid=676237

HAT是有力的JAVA分析工具。具体

参考文档  https://hat.dev.java.net/doc/README.html

在jvm option加入参数先作thread dump，再用hat 分析结果

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/home/admin/work/intl-myalibaba/deploy/heap.dump

启动服务

java -Xms2048m -Xmx2048m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=64m -XX:MaxPermSize=64m -jar ./hat.jar heap.hprof

ie浏览器察看

http://localhost:7002/

系统一HTML：

<form action="" method="post" enctype="multipart/form-data">
<input type="hidden" name="action" value="/task/task_pool_process_image_achive_action" />
<input name="event_submit_do_upload" type="hidden" value="

 录制下来的脚本：

web_submit_data("process_image_achive.htm",

  "Action=http://bops.alibaba.net:8888/allTask/process_image_achive.htm",

  "Method=POST",

  "EncType=multipart/form-data",

  "RecContentType=text/html",

  "Referer=http://bops.alibaba.net:8888/allTask/process_image_achive.htm",

  "Snapshot=t11.inf",

  "Mode=HTML",

  ITEMDATA,

  "Name=action", "Value=/task/task_pool_process_image_achive_action", ENDITEM,

  "Name=event_submit_do_upload", "Value=anything", ENDITEM,

  "Name=actionEvent", "Value=imageAchieve", ENDITEM,

  "Name=_fmcr.pro._0.o", "Value=company", ENDITEM,

  "Name=_fmcr.pro._0.a", "Value=D:\\NCom_070723_212112_49.zip", "File=yes", ENDITEM,

  "Name=addnew", "Value=yes", ENDITEM,

  "Name=Submit1", "Value= 纭"

  "\\xAE"

  " 瀹"

  "\\x9A"

  "(O) ", ENDITEM,

系统2 的HTML

 录制下来的脚本如下

web_custom_request("save_company.htm",

  "URL=http://hz.my.alibaba.com/newborn/save_company.htm",

  "Method=POST",

  "Resource=0",

  "RecContentType=text/html",

  "Referer=http://hz.my.alibaba.com/newborn/save_company.htm",

  "Snapshot=t7.inf",

  "Mode=HTML",

  "EncType=multipart/form-data; boundary=---------------------------7d738225c60e78",

  "BodyBinary=-----------------------------7d738225c60e78\r\n"

  "Content-Disposition: form-data; name=\"action\"\r\n"

  ...

 "Content-Disposition: form-data; name=\"_fmn.sav._0.l\"; filename=\"D:"

  "\\x5C"

  "鍥介檯绔欐敼閫燶pic"

  "\\x5C"

  "NCom_070613_052134_266"

  "\\x5C"

  "company"

  "\\x5C"

  "70000151_aboutus1.JPG\"\r\n"

  "Content-Type: image/pjpeg\r\n"

  "\r\n"

  "\\xFF\\xD8\\xFF\\xE0\\x00\\x10"

  "JFIF"

2种脚本都能正常工作，

mod_jk.log 大量

调整前的

 cat  workers.properties.bak
worker.list=ajp13              
worker.ajp13.port=5081         
worker.ajp13.host=127.0.0.1
worker.ajp13.type=ajp13

Server.xml采用默认值。

从症状看，不是程序的问题，是mod_jk配置有误。也不是版本失配。

jboss的tomcat配置加了这一段，maxThreads="350" maxProcessors="350" minSpareThreads="30" backlog="400" connectionTimeout="600000"

apache  mod_jk  worker.property 增加pool的控制。 默认是一个连接。

worker.localnode.lbfactor=1

worker.localnode.connection_pool_size=50

worker.localnode.connection_pool_minsize=25

worker.localnode.connection_pool_timeout=600
# Load-balancing behaviour
worker.loadbalancer.type=lb
worker.loadbalancer.balance_workers=localnode
# Status worker for managing load balancer
worker.status.type=status

 loadrunner 有专门的j2ee 诊断模块，可以降低性能分析瓶颈难度、透明化瓶颈环节。

1.1.      访问diagnositic  server

Loadrunner 8.1光盘里面有介质

无多台diagnostic时，选择commander 模式安装介质。

http://127.0.0.1:2006/

或者远程 http://10.0.32.122:2006/  ，默认帐号是 admin

1.2.      安装j2ee  probe

选取diagnostic server为10.0.32.122

安装在C:\MercuryDiagnostics\JAVAProbe\，

startAgent.cmd 为启动代理，以便推送probe信息给server

profiler.cmd   启动profiler

http://127.0.0.1:35000 可以诊断probe是否安装好了

配置文件位于 C:\MercuryDiagnostics\JAVAProbe\etc

1.3.      与loadrunner集成

Loadrunner  license 管理器->configure  j2ee diagnostic

但需要License.

临时License 可以向hp mi 销售申请。

float  prevValue;

float      currValue;

为了判断2个float 类型是否相等。

if  (currValue == prevValue) 这种写法是有缺陷的。

比较大小可以修改为： (prevValue + currValue - pBestProbs[endIndexT]) < 0.000000001
double存放格式是包括符号位、幂数、系数组成。 

 if(preValue + currValue - pBestProbs[endIndexT] < 0.000000001) { //如果概率大