What is ThreadLocal memory leak and how to solve it

 

Solid lines represent strong quotes , Dashed lines represent weak references

every last Thread Maintain a ThreadLocalMap, key For the use of Weak reference Of ThreadLocal example ,value Is a copy of the thread variable .

Strong citation , Use the most common quotation , An object has a strong reference , It won't be recycled by the garbage collector . When memory runs out of space ,Java The virtual machine would rather throw OutOfMemoryError error , Causes the program to terminate abnormally , And don't recycle the object .

If you want to disassociate a strong reference from an object , You can explicitly assign references to null, This will enable JVM The object will be recycled at the right time .

Weak reference ,JVM When recycling , Whether the memory is sufficient or not , All objects associated with weak references will be recycled . stay java in , use java.lang.ref.WeakReference Class .