Mixing
should Class.getResourceAsStream be closed?
I was wondering if this is required since when i use this method, the file is being read from the classpath. Does "not closing" it lead to a memory leak.
How can i test for such memory leaks?
java
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
add a comment |
I was wondering if this is required since when i use this method, the file is being read from the classpath. Does "not closing" it lead to a memory leak.
How can i test for such memory leaks?
java
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
add a comment |
I was wondering if this is required since when i use this method, the file is being read from the classpath. Does "not closing" it lead to a memory leak.
How can i test for such memory leaks?
java
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
I was wondering if this is required since when i use this method, the file is being read from the classpath. Does "not closing" it lead to a memory leak.
How can i test for such memory leaks?
java
java
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
asked Oct 25 '13 at 19:36
BobLoblawBobLoblaw
6801921
6801921
add a comment |
add a comment |
3 Answers
3
active
oldest
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You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).
Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...
Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.
As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
add a comment |
As a rule of thumb you should close all streams (and ay other types that provide close functionality). It can lead ro resource leaks (memory is one type of resource).
Although there is automatic garbage collection that reclaims memory eventually when an object is no longer referred to, it might still hold native resources that might not be released. Also, if some other long-lived object (e.g. the classloader) keeps a hold on the resource, it will not be claimed by the garbage collector.
If your program is short lived, or f you only open a small number of resources, you might not run into problems, but resource leaks are hard to detect in long-running applications.
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
add a comment |
The type returned is an inputstream so, regardless the concrete implementation (which could change from version to version), you have a close() method that imho should be called.
No matter if that method is actually doing something useful with the current version.
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).
Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...
Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.
As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
add a comment |
You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).
Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...
Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.
As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
add a comment |
You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).
Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...
Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.
As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).
Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...
Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.
As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
edited Jun 21 '18 at 17:44
The Alchemist
3,0541319
3,0541319
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
answered Oct 25 '13 at 19:41
jwatkinsjwatkins
1,757619
1,757619
add a comment |
add a comment |
As a rule of thumb you should close all streams (and ay other types that provide close functionality). It can lead ro resource leaks (memory is one type of resource).
Although there is automatic garbage collection that reclaims memory eventually when an object is no longer referred to, it might still hold native resources that might not be released. Also, if some other long-lived object (e.g. the classloader) keeps a hold on the resource, it will not be claimed by the garbage collector.
If your program is short lived, or f you only open a small number of resources, you might not run into problems, but resource leaks are hard to detect in long-running applications.
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
add a comment |
As a rule of thumb you should close all streams (and ay other types that provide close functionality). It can lead ro resource leaks (memory is one type of resource).
Although there is automatic garbage collection that reclaims memory eventually when an object is no longer referred to, it might still hold native resources that might not be released. Also, if some other long-lived object (e.g. the classloader) keeps a hold on the resource, it will not be claimed by the garbage collector.
If your program is short lived, or f you only open a small number of resources, you might not run into problems, but resource leaks are hard to detect in long-running applications.
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
add a comment |
As a rule of thumb you should close all streams (and ay other types that provide close functionality). It can lead ro resource leaks (memory is one type of resource).
Although there is automatic garbage collection that reclaims memory eventually when an object is no longer referred to, it might still hold native resources that might not be released. Also, if some other long-lived object (e.g. the classloader) keeps a hold on the resource, it will not be claimed by the garbage collector.
If your program is short lived, or f you only open a small number of resources, you might not run into problems, but resource leaks are hard to detect in long-running applications.
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
As a rule of thumb you should close all streams (and ay other types that provide close functionality). It can lead ro resource leaks (memory is one type of resource).
Although there is automatic garbage collection that reclaims memory eventually when an object is no longer referred to, it might still hold native resources that might not be released. Also, if some other long-lived object (e.g. the classloader) keeps a hold on the resource, it will not be claimed by the garbage collector.
If your program is short lived, or f you only open a small number of resources, you might not run into problems, but resource leaks are hard to detect in long-running applications.
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
answered Oct 25 '13 at 19:42
AttilaAttila
22.5k13245
22.5k13245
add a comment |
add a comment |
The type returned is an inputstream so, regardless the concrete implementation (which could change from version to version), you have a close() method that imho should be called.
No matter if that method is actually doing something useful with the current version.
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
add a comment |
The type returned is an inputstream so, regardless the concrete implementation (which could change from version to version), you have a close() method that imho should be called.
No matter if that method is actually doing something useful with the current version.
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
add a comment |
The type returned is an inputstream so, regardless the concrete implementation (which could change from version to version), you have a close() method that imho should be called.
No matter if that method is actually doing something useful with the current version.
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
The type returned is an inputstream so, regardless the concrete implementation (which could change from version to version), you have a close() method that imho should be called.
No matter if that method is actually doing something useful with the current version.
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
answered Oct 25 '13 at 19:40
AndreaAndrea
1,89421929
1,89421929
add a comment |
add a comment |
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