内存泄漏，适用于Android的Spring

Question

I have a potential memory leak at my code and I'm trying to find a solution. I'm using the Spring for Android framework. And more specific the

  RestTemplate.exchange();

In order to make an on the fly binding. However, when i make a memory analysis I get the following:

1.628 instances of "com.products.Product", loaded by "dalvik.system.PathClassLoader @ 0x43692b80" occupy 1.363.064 (22,20%) bytes. These instances are referenced from one instance of "java.lang.Object[]", loaded by "". The dominator tree is the following:

class com.products.ProductList @ 0x436d7ea8 System Class| 1.628 | 8 | 130.240 | 8

mFilteredProducts java.util.ArrayList @ 0x43a4eab0| 1.628 | 24 | 130.240 | 6.552

array java.lang.Object[1628] @ 0x43bdc888| 1.628 | 6.528 | 130.240 | 6.528

[274] com.products.Product @ 0x4398b038| 1 | 80 | 80 | 760

[1175] com.products.Product @ 0x43b26868| 1 | 80 | 80 | 808

........

The above one is the dominator tree. However I was wondering if there is a safe way to activate the garbage collector. Is the

  System.gc();

Safe? However,is there a way to stop taking this memory leak? The class com.products.Product is just a simple POJO which will bind the JSON fields to the corresponding attributes. Generally the POJO that is used to bind the JSON is as following:

@JsonIgnoreProperties(ignoreUnknown = true) //must be there all times most likely
public class MyPojo {

@JsonProperty("Products")
private ArrayList<Product> products;

public ArrayList<Product> getProducts() {
    return products;
}

public void setProducts(ArrayList<Product> products) {
    this.products = products;
}
}

com.products.Product:

@JsonIgnoreProperties(ignoreUnknown = true) //must be there all times most likely
public class Products {

 @JsonProperty
 private String prodnum;
 @JsonProperty
 private String brand;
 @JsonProperty
 private String name;

       //get/set
}

Answer 1

Calling System.gc() is safe. But it doesn't necessarily trigger the actual garbage collection. Calling this method only suggests JVM to make all the efforts to perform garbage collection. There is no way in Java to force it though.

Regarding the memory leak. Look at the ProductList , why is it holding all those objects. If ProductList is still referenced from anywhere in your application all those products will not be released.

Answer 2

System.gc() is safe as @wajda already said

Today I had similar problem with desktop application and the problem was that I wasn't closing PreparedStatement and ResultSet objects after usage. After about 600 queries I filled up 256mb of allocated space. After using JVisualVM (you should have it in your JDK) and analyzing what is piling up, I saw char arrays taking 80% of space and they were all empty.

Try and close all JSON objects after each usage and see if it helps.

Cheers