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我们有一段代码，它根据 mysql 定义的函数进行选择。我们发现，一旦启用这部分runtime.totalMemory() ，使用的内存就会不断增加。下面是代码片段。问题从String selectQuery4. 知道为什么这是一个问题吗？

double currentLong = Double.parseDouble(longitude);
double currentLat = Double.parseDouble(latitude); 

Statement stmt6 = null;
stmt6 = dbconn.createStatement(); 

String selectQuery3 = "Select geoFenceID,enterpriseID,clientID,geoFenceString,geoFenceType,geoFenceName,geoFenceDescription,geoFencePreference, geoFenceRadius From tblGeoFence Where ((enterpriseID="+enterpriseID+" And clientID=0) Or (enterpriseID="+enterpriseID+" And clientID="+clientID+")) And geoFenceStatus='a'"; 
ResultSet rs3 = stmt6.executeQuery(selectQuery3);

while(rs3.next()) {
    geoFenceID = rs3.getInt("geoFenceID");
    geoFenceType = rs3.getString("geoFenceType");
    geoFenceString = rs3.getString("geoFenceString");
    geoFenceRadius = rs3.getInt("geoFenceRadius");
    geoFencePreference = rs3.getString("geoFencePreference");
    String polygon  =  "GeomFromText('"+geoFenceString+"')";
    String point    =  "GeomFromText('POINT("+currentLong+"  "+currentLat+")')";

    Statement stmt7 = null;
    stmt7 = dbconn.createStatement();
    String selectQuery4 = "SELECT GISWithin("+point+","+polygon+") As geoFenceStatus";
    ResultSet rs4 = stmt7.executeQuery(selectQuery4);

    if(rs4.next()) {

        if(rs4.getInt("geoFenceStatus")==1) {

            geoFenceIDFound=geoFenceID;
            geoFenceName = rs3.getString("geoFenceName");
            geoFenceDescription = rs3.getString("geoFenceDescription");                                                     
            geoFencePreference = rs3.getString("geoFencePreference");   

            if(lastGeoFenceID==geoFenceID) {
                geoFenceInID = geoFenceID;                  
                break;
            } else {

                if(previousGeoFenceID==geoFenceID &&(previousTimeDifferenceInt<0 || geoFenceArriveTimeDifferenceInt <= 0)) //check the funny problem double entry back into the geo fence
                {
                    lastGeoFenceID=geoFenceID;
                    geoFenceInID = geoFenceID;
                    break;
                } else {
                    geoFenceAlertEmailMessage="\nGeo Fence Alert Arrival\nTime:"+dateTimer+"\nGeo Fence Name :"+geoFenceName+"\nGeo Fence Description :"+geoFenceDescription+"\nGeo Fence Preference:"+geoFencePreference;

                    if(lastGeoFenceEntryStatus.equals("") || lastGeoFenceEntryStatus.equals("Out")) {
                        geoFenceEntryStatus="In";
                    } else {
                        geoFenceEntryStatus="Out";
                    }
                }
            }
        }
    }
}

try {
    if ( rs4 != null ) {
        rs4.close();
    }                                        
    if ( stmt7!= null ) {
        stmt7.close();
    }
} catch(SQLException ex) {
    ex.printStackTrace(System.out);
}             
}           
try {
    if ( rs3 != null ) {
        rs3.close();
    }                              
    if ( stmt6!= null ){
        stmt6.close();
    }                              
} catch(SQLException ex) {
    ex.printStackTrace(System.out);
}

用于打印内存统计信息的代码。

int mb = 1024*1024;
System.out.println("##### Heap utilization statistics [MB] #####");

//Print used memory
System.out.println("Used Memory:" + (runtime.totalMemory() - runtime.freeMemory()) / mb);

//Print free memory
System.out.println("Free Memory:" + runtime.freeMemory() / mb);

//Print total available memory
System.out.println("Total Memory:" + runtime.totalMemory() / mb);

//Print Maximum available memory
System.out.println("Max Memory:" + runtime.maxMemory() / mb);
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1 回答 1

5

您的代码应该在 try/finally 块中调用 close。您还应该在字符串中使用 PreparedSTatements 而不是参数 concat。

关于您的问题，不确定您是否有问题：

  • 你的第一个 while 循环做了多少次迭代？

  • 使用 jconsole 连接到您的 jvm 并在循环结束后调用垃圾收集以查看内存是否下降：

  • 如果是这样，那么您就没有真正的铅

  • 如果没有，那么你有

问候

于 2012-08-20T06:09:45.403 回答