Summary of memory overflow Exception Solutions

These days, I have encountered a Java memory overflow problem. I have been trying to solve this problem. Now I think of three methods: Adjusting virtual machine parameters, releasing useless objects immediately, and using serialization and deserialization technologies.

The following is the specific code implementation:

Package com. Free;

Import java. Io. file;

Import java. Io. fileinputstream;

Import java. Io. filenotfoundexception;

Import java. Io. fileoutputstream;

Import java. Io. ioexception;

Import java. Io. objectinputstream;

Import java. Io. objectoutputstream;

Import java. Math. biginteger;

Import java. util. arraylist;

Import java. util. List;

/**

* @ Author free

* Springcomingagain@gmail.com

*/

Public class outmemorysolution {

/***

* Change JVM arguments

* Adjust VM Parameters

*

*

 
　　*

 

* First try

*

*-Xloggc: GC. Log

*-Xms256m

*-Xmx256m

*

* Throw java. Lang. outofmemoryerror: Java heap Space

*

*

 

* Second try

*

*-Xloggc: GC. Log

*-Xms512m

*-Xmx512m

*

*

 

*/

Public static void changejvmarguments (){

Long starttime = system. currenttimemillis ();

System. Out. println ("START:" + starttime );

List List = new arraylist (0 );

For (INT I = 0; I <5000000; I ++ ){

List. Add (New biginteger ("1000000 "));

}

Long endtime = system. currenttimemillis ();

System. Out. println ("End...:" + endtime + "cost :"

+ (Endtime-starttime ));

}

/**

* Release object immediate

* Release useless objects immediately

*

 
　　*

 

* Release object

*

*

* // First release object

* Biginteger temp1 = NULL;

* For (INT I = 0; I <1200000; I ++ ){

* Temp1 = array1 [I];

* Temp1 = NULL;

* Array1 [I] = NULL;

*}

* Array1 = NULL;

*...

* // Second release object

* Temp1 = NULL;

* For (INT I = 0; I <1200000; I ++ ){

* Temp1 = array2 [I];

* Temp1 = NULL;

* Array2 [I] = NULL;

*}

* Array2 = NULL;

*

*

 

*/

Public static void releaseobjectimmediate (){

Long starttime = system. currenttimemillis ();

System. Out. println ("first start:" + starttime );

Biginteger [] array1 = new biginteger [1200000];

For (INT I = 0; I <1200000; I ++ ){

Array1 [I] = new bigint ("10000000 ");

}

// First release object

Biginteger temp1 = NULL;

For (INT I = 0; I <1200000; I ++ ){

Temp1 = array1 [I];

Temp1 = NULL;

Array1 [I] = NULL;

}

Array1 = NULL;

Long endtime = system. currenttimemillis ();

System. Out. println ("first end...:" + endtime + "cost :"

+ (Endtime-starttime ));

// Do something start

// Do something end ..

Starttime = system. currenttimemillis ();

System. Out. println ("second start:" + starttime );

Biginteger [] array2 = new biginteger [2, 1200000];

For (INT I = 0; I <1200000; I ++ ){

Array2 [I] = new bigint ("10000000 ");

}

// Second release object

Temp1 = NULL;

For (INT I = 0; I <1200000; I ++ ){

Temp1 = array2 [I];

Temp1 = NULL;

Array2 [I] = NULL;

}

Array2 = NULL;

Endtime = system. currenttimemillis ();

System. Out. println ("second end...:" + endtime + "cost :"

+ (Endtime-starttime ));

}

/**

* Delaysave

* Serialization and deserialization Technologies

*

Store object

 

*

Read object

 

*

Do something

 

*/

@ Suppresswarnings ("unchecked ")

Public static void delaysave (){

Final string objectstorefolder = "D: \ OBJ \\";

System. Out. println ("store object start ..");

// Store object serialized object

Objectoutputstream out = NULL;

Try {

Out = new objectoutputstream (New fileoutputstream (

Objectstorefolder + "objectfile. OBJ" + 0 ));

List List = new arraylist (0 );

For (INT I = 0; I <5000000; I ++ ){

If (I + 1) % 100000) = 0 ){

Out. writeobject (list );

Out. Close ();

Out = NULL;

List = NULL;

List = new arraylist (0 );

Out = new objectoutputstream (New fileoutputstream (

Objectstorefolder + "objectfile. OBJ" + (I % 1000000) + 1 )));

}

System. Out. println (I );

List. Add (New biginteger ("1000000 "));

}

} Catch (filenotfoundexception e ){

System. Err. println (E. getmessage ());

} Catch (ioexception e ){

System. Err. println (E. getmessage ());

}

Finally {

If (null! = Out ){

Try {

Out. Close ();

Out = NULL;

} Catch (ioexception e ){

// Ignore

}

}

}

System. Out. println ("store object end ..");

System. Out. println ("read object start ..");

// Read object deserialization object

File [] filelist = new file (objectstorefolder). listfiles ();

Int filesize = filelist. length;

Objectinputstream in = NULL;

Try {

For (INT I = 0; I <filesize; I ++ ){

In = new objectinputstream (

New fileinputstream (filelist [I]);

List List = (list ) In. readobject ();

// Do something start

System. Out. println (list. Size ());

// Do something end ..

}

} Catch (filenotfoundexception e ){

System. Err. println (E. getmessage ());

} Catch (ioexception e ){

System. Err. println (E. getmessage ());

} Catch (classnotfoundexception e ){

System. Err. println (E. getmessage ());

}

Finally {

If (null! = In ){

Try {

In. Close ();

In = NULL;

} Catch (ioexception e ){

// Ignore

}

}

}

System. Out. println ("read object end ..");

}

/**

* Test code

* @ Param ARGs

*/

Public static void main (string [] ARGs ){

Changejvmarguments ();

Releaseobjectimmediate ();

Delaysave ();

}

}