Who consumes more memory, ArrayList or HashSet / LinkedHashSet?
I have a very huge collection, so even relatively small memory difference can make difference.
Or the difference is minimal?
Does memory consumtion growth differently when we add more elements?
I believe that LinkedHashSet eats more memory per N elements than HashSet (to store linked-list links), but I cannot compare ArrayList to HashSet.
java collections
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
add a comment |
I have a very huge collection, so even relatively small memory difference can make difference.
Or the difference is minimal?
Does memory consumtion growth differently when we add more elements?
I believe that LinkedHashSet eats more memory per N elements than HashSet (to store linked-list links), but I cannot compare ArrayList to HashSet.
java collections
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
2
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00
add a comment |
I have a very huge collection, so even relatively small memory difference can make difference.
Or the difference is minimal?
Does memory consumtion growth differently when we add more elements?
I believe that LinkedHashSet eats more memory per N elements than HashSet (to store linked-list links), but I cannot compare ArrayList to HashSet.
java collections
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
I have a very huge collection, so even relatively small memory difference can make difference.
Or the difference is minimal?
Does memory consumtion growth differently when we add more elements?
I believe that LinkedHashSet eats more memory per N elements than HashSet (to store linked-list links), but I cannot compare ArrayList to HashSet.
java collections
java collections
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
asked Nov 15 '18 at 16:27
caasdadscaasdads
1347
1347
2
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00
add a comment |
2
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00
2
2
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00
add a comment |
1 Answer
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Typically, a HashMap uses 32 bytes per entry (12 bytes header + 16 bytes data + 4 bytes padding). It will also use 4 * the capacity bytes, so when it's all said and done a HashMap object will occupy
32 * size + 4 * capacity bytes
An ArrayList on the other hand generally allocates 4-8 bytes per entry. This can be more however, if you allocate a bigger capacity of the ArrayList, and only hold a few elements.
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
add a comment |
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1 Answer
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Typically, a HashMap uses 32 bytes per entry (12 bytes header + 16 bytes data + 4 bytes padding). It will also use 4 * the capacity bytes, so when it's all said and done a HashMap object will occupy
32 * size + 4 * capacity bytes
An ArrayList on the other hand generally allocates 4-8 bytes per entry. This can be more however, if you allocate a bigger capacity of the ArrayList, and only hold a few elements.
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
add a comment |
Typically, a HashMap uses 32 bytes per entry (12 bytes header + 16 bytes data + 4 bytes padding). It will also use 4 * the capacity bytes, so when it's all said and done a HashMap object will occupy
32 * size + 4 * capacity bytes
An ArrayList on the other hand generally allocates 4-8 bytes per entry. This can be more however, if you allocate a bigger capacity of the ArrayList, and only hold a few elements.
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
add a comment |
Typically, a HashMap uses 32 bytes per entry (12 bytes header + 16 bytes data + 4 bytes padding). It will also use 4 * the capacity bytes, so when it's all said and done a HashMap object will occupy
32 * size + 4 * capacity bytes
An ArrayList on the other hand generally allocates 4-8 bytes per entry. This can be more however, if you allocate a bigger capacity of the ArrayList, and only hold a few elements.
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
Typically, a HashMap uses 32 bytes per entry (12 bytes header + 16 bytes data + 4 bytes padding). It will also use 4 * the capacity bytes, so when it's all said and done a HashMap object will occupy
32 * size + 4 * capacity bytes
An ArrayList on the other hand generally allocates 4-8 bytes per entry. This can be more however, if you allocate a bigger capacity of the ArrayList, and only hold a few elements.
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
answered Nov 15 '18 at 16:45
GBlodgettGBlodgett
10.7k42136
10.7k42136
add a comment |
add a comment |
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2
ArrayList typically uses 4-8 bytes per reference, HashSet typically uses ~32 bytes. Unless you have hundreds of millions of values, it might not make as much difference as you think.
– Peter Lawrey
Nov 15 '18 at 16:29
There are quite a few collection libraries that aim to be more memory efficient than standard java collection implementations, which you might find useful. Some examples are fastutil, Trove and Eclipse Collections
– kapex
Nov 15 '18 at 17:00