Ruby大数组和内存 [英] Ruby big array and memory
问题描述
我创建了一个大数组a，其内存增加到约500 MB:
a = []
t = Thread.new do
loop do
sleep 1
print "#{a.size} "
end
end
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
t.join
在那之后，我清除"了a，但是直到我终止了该进程，分配的内存才发生变化.我需要做些特别的事情来从内存中删除分配给a的所有这些数据吗?
如果我使用 Ruby Garbage Collection Profiler (对代码进行了轻微修改的版本):
GC::Profiler.enable
GC::Profiler.clear
a = []
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
GC::Profiler.report
我得到以下输出(在Ruby 1.9.3上)(删除了某些列和行):
GC 60 invokes.
Index Invoke Time(sec) Use Size(byte) Total Size(byte) ...
1 0.109 131136 409200 ...
2 0.125 192528 409200 ...
...
58 33.484 199150344 260938656 ...
59 36.000 211394640 260955024 ...
配置文件以使用的131136字节开始，以使用的211394640字节结束，并且在运行中任何地方都没有减小大小，我们可以假定没有进行垃圾收集.
如果我随后添加一行代码，则将一个元素添加到数组a中，放置在a增长到500万个元素之后，然后为其分配了一个空数组:
GC::Profiler.enable
GC::Profiler.clear
a = []
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
# the only change is to add one element to the (now) empty array a
a << [rand(36**10).to_s(36)]
GC::Profiler.report
这会将事件探查器的输出更改为(已删除某些列和行):
GC 62 invokes.
Index Invoke Time(sec) Use Size(byte) Total Size(byte) ...
1 0.156 131376 409200 ...
2 0.172 192792 409200 ...
...
59 35.375 211187736 260955024 ...
60 36.625 211395000 469679760 ...
61 41.891 2280168 307832976 ...
现在，此探查器运行开始于使用的131 376字节开始，与之前的运行类似，但会增加，但以使用2 280 168字节结束，大大低于之前的使用211 394 640字节结束的配置文件运行，可以假定垃圾收集是在此运行期间发生的，这可能是由我们的新代码行触发的，该代码行向a添加了元素.
简短的回答是否"，您无需执行任何特殊操作即可删除分配给a的数据，但是希望这可以为您提供证明它的工具.
I created a big array a, whose memory grew to ~500 MB:
a = []
t = Thread.new do
loop do
sleep 1
print "#{a.size} "
end
end
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
t.join
After that, I "cleared" a, but the allocated memory didn't change until I killed the process. Is there something special I need to do to remove all these data which were assigned to a from the memory?
If I use the Ruby Garbage Collection Profiler on a lightly modified version of your code:
GC::Profiler.enable
GC::Profiler.clear
a = []
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
GC::Profiler.report
I get the following output (on Ruby 1.9.3)(some columns and rows removed):
GC 60 invokes.
Index Invoke Time(sec) Use Size(byte) Total Size(byte) ...
1 0.109 131136 409200 ...
2 0.125 192528 409200 ...
...
58 33.484 199150344 260938656 ...
59 36.000 211394640 260955024 ...
The profile starts with 131 136 bytes used, and ends with 211 394 640 bytes used, without decreasing in size anywhere in the run, we can assume that no garbage collection has taken place.
If I then add a line of code which adds a single element to the array a, placed after a has grown to 5 million elements, and then has an empty array assigned to it:
GC::Profiler.enable
GC::Profiler.clear
a = []
5_000_000.times do
a << [rand(36**10).to_s(36)]
end
puts "\n size is #{a.size}"
a = []
# the only change is to add one element to the (now) empty array a
a << [rand(36**10).to_s(36)]
GC::Profiler.report
This changes the profiler output to (some columns and rows removed):
GC 62 invokes.
Index Invoke Time(sec) Use Size(byte) Total Size(byte) ...
1 0.156 131376 409200 ...
2 0.172 192792 409200 ...
...
59 35.375 211187736 260955024 ...
60 36.625 211395000 469679760 ...
61 41.891 2280168 307832976 ...
This profiler run now starts with 131 376 bytes used, which is similar to the previous run, grows, but ends with 2 280 168 bytes used, significantly lower than the previous profile run that ended with 211 394 640 bytes used, we can assume that garbage collection took place this during this run, probably triggered by our new line of code that adds an element to a.
The short answer is no, you don't need to do anything special to remove the data that was assigned to a, but hopefully this gives you the tools to prove it.
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