我正在尝试使用Java Servlet和mysql（innoDB引擎）和码头服务器开发客户端服务器聊天应用程序。我使用jmeter测试了100个模拟用户一次访问服务器的连接代码，但平均时间为40秒：（对于所有这些用户而言，连接时间都分别为线程（2秒）和最短时间（80秒）我的连接数据库表具有以下结构，即两列connect（user，stranger），我的servlet代码如下所示：我使用innoDB引擎进行行级锁定。我还使用了显式写锁定SELECT ...... FOR事务内部的更新。如果由于死锁而回滚，直到事务至少执行一次，我将循环该事务。一旦两个用户建立连接，他们将使用彼此随机生成的唯一编号更新其陌生人的列。
我正在使用c3p0连接池，其中至少有100个线程处于打开状态，而码头则具有至少100个线程。
请帮助我确定瓶颈或找到瓶颈所需的工具。
import java.io.*;
import java.util.*;
import java.sql.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.naming.*;
import javax.sql.*;
public class connect extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws java.io.IOException {
String unumber=null;
String snumber=null;
String status=null;
InitialContext contxt1=null;
DataSource ds1=null;
Connection conxn1=null;
PreparedStatement stmt1=null;
ResultSet rs1=null;
PreparedStatement stmt2=null;
InitialContext contxt3=null;
DataSource ds3=null;
Connection conxn3=null;
PreparedStatement stmt3=null;
ResultSet rs3=null;
PreparedStatement stmt4=null;
ResultSet rs4=null;
PreparedStatement stmt5=null;
boolean checktransaction = true;
unumber=req.getParameter("number"); // GET THE USER's UNIQUE NUMBER
try {
contxt1 = new InitialContext();
ds1 =(DataSource)contxt1.lookup("java:comp/env/jdbc/user");
conxn1 = ds1.getConnection();
stmt1 = conxn1.prepareStatement("SELECT * FROM profiles WHERE number=?"); // GETTING USER DATA FROM PROFILE
stmt1.setString(1,unumber);
rs1 = stmt1.executeQuery();
if(rs1.next()) {
res.getWriter().println("user found in PROFILE table.........");
uage=rs1.getString("age");
usex=rs1.getString("sex");
ulocation=rs1.getString("location");
uaslmode=rs1.getString("aslmode");
stmt1.close();
stmt1=null;
conxn1.close();
conxn1 = null;
contxt3 = new InitialContext();
ds3 =(DataSource)contxt3.lookup("java:comp/env/jdbc/chat");
conxn3 = ds3.getConnection();
conxn3.setAutoCommit(false);
while(checktransaction) {
// TRANSACTION STARTS HERE
try {
stmt2 = conxn3.prepareStatement("INSERT INTO "+ulocation+" (user,stranger) VALUES (?,'')"); // INSERTING RECORD INTO LOCAL CHAT TABLE
stmt2.setString(1,unumber);
stmt2.executeUpdate();
stmt2.close();
stmt2 = null;
res.getWriter().println("inserting row into LOCAL CHAT TABLE.........");
System.out.println("transaction starting........."+unumber);
stmt3 = conxn3.prepareStatement("SELECT user FROM "+ulocation+" WHERE (stranger='' && user!=?) LIMIT 1 FOR UPDATE");
stmt3.setString(1,unumber); // SEARCHING FOR STRANGER
rs3=stmt3.executeQuery();
if (rs3.next()) { // stranger found
stmt4 = conxn3.prepareStatement("SELECT stranger FROM "+ulocation+" WHERE user=?");
stmt4.setString(1,unumber); //CHECKING FOR USER STATUS BEFORE CONNECTING TO STRANGER
rs4=stmt4.executeQuery();
if(rs4.next()) {
status=rs4.getString("stranger");
}
stmt4.close();
stmt4=null;
if(status.equals("")) { // user status is also null
snumber = rs3.getString("user");
stmt5 = conxn3.prepareStatement("UPDATE "+ulocation+" SET stranger=? WHERE user=?"); // CONNECTING USER AND STRANGER
stmt5.setString(1,snumber);
stmt5.setString(2,unumber);
stmt5.executeUpdate();
stmt5.setString(2,snumber);
stmt5.setString(1,unumber);
stmt5.executeUpdate();
stmt5.close();
stmt5=null;
}
} // end of stranger found
stmt3.close();
stmt3 = null;
conxn3.commit(); // TRANSACTION ENDING
checktransaction = false;
} // END OF TRY INSIDE WHILE
catch(java.sql.SQLTransactionRollbackException e) {
System.out.println("transaction restarted......."+unumber);
counttransaction = counttransaction+1;
}
} //END OF WHILE LOOP
conxn3.close();
conxn3 = null;
} // END OF USER FOUND IN PROFILE TABLE
} // end of try
catch(java.sql.SQLException sqlexe) {
try {conxn3.rollback();}
catch(java.sql.SQLException exe) {conxn3=null;}
sqlexe.printStackTrace();
res.getWriter().println("UNABE TO GET CONNECTION FROM POOL!");
}
catch(javax.naming.NamingException namexe) {
namexe.printStackTrace();
res.getWriter().println("DATA SOURCE LOOK UP FAILED!");
}
}
}
最佳答案
您有几个用户？您可以先将它们全部加载到内存中并进行内存查找吗？
如果您将数据库层与表示层分开，则可以在不更改servlet的情况下进行更改（因为它不在乎数据来自何处）
如果您使用Java内存，则每个用户的时间不应超过20毫秒。
此测试可在内存中创建一百万个配置文件，查找它们并创建聊天条目，然后将其删除。每次操作的平均时间为640 ns（纳秒或十亿分之一秒）
import java.util.LinkedHashMap;
import java.util.Map;
public class Main {
public static void main(String... args) {
UserDB userDB = new UserDB();
// add 1000,000 users
for (int i = 0; i < 1000000; i++)
userDB.addUser(
new Profile(i,
"user+i",
(short) (18 + i % 90),
i % 2 == 0 ? Profile.Sex.Male : Profile.Sex.Female,
"here", "mode"));
// lookup a users and add a chat session.
long start = System.nanoTime();
int operations = 0;
for(int i=0;i<userDB.profileCount();i+=2) {
Profile p0 = userDB.getProfileByNumber(i);
operations++;
Profile p1 = userDB.getProfileByNumber(i+1);
operations++;
userDB.chatsTo(i, i+1);
operations++;
}
for(int i=0;i<userDB.profileCount();i+=2) {
userDB.endChat(i);
operations++;
}
long time = System.nanoTime() -start;
System.out.printf("Average lookup and update time per operation was %d ns%n", time/operations);
}
}
class UserDB {
private final Map<Long, Profile> profileMap = new LinkedHashMap<Long, Profile>();
private final Map<Long, Long> chatsWith = new LinkedHashMap<Long, Long>();
public void addUser(Profile profile) {
profileMap.put(profile.number, profile);
}
public Profile getProfileByNumber(long number) {
return profileMap.get(number);
}
public void chatsTo(long number1, long number2) {
chatsWith.put(number1, number2);
chatsWith.put(number2, number1);
}
public void endChat(long number) {
Long other = chatsWith.get(number);
if (other == null) return;
Long number2 = chatsWith.get(other);
if (number2 != null && number2 == number)
chatsWith.remove(other);
}
public int profileCount() {
return profileMap.size();
}
}
class Profile {
final long number;
final String name;
final short age;
final Sex sex;
final String location;
final String aslmode;
Profile(long number, String name, short age, Sex sex, String location, String aslmode) {
this.number = number;
this.name = name;
this.age = age;
this.sex = sex;
this.location = location;
this.aslmode = aslmode;
}
enum Sex {Male, Female}
}
版画
Average lookup and update time per operation was 636 ns
如果您需要更快的速度，可以考虑使用Trove4j，在这种情况下，速度可能是原来的两倍。考虑到这可能足够快，我将尝试使事情保持简单。
关于java - 100个用户的JAVA MYSQL聊天性能问题，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/6667383/