OutOfMemoryError系列（6）: Out of swap space？
https://blog.csdn.net/renfufei/article/details/78136638
This is the sixth article in this series, a list of related articles:
- OutOfMemoryError系列（1）: Java heap space
- OutOfMemoryError系列（2）: GC overhead limit exceeded
- OutOfMemoryError系列（3）: Permgen space
- OutOfMemoryError系列（4）: Metaspace
- OutOfMemoryError系列（5）: Unable to create new native thread
JVM startup parameter specifies the maximum memory limit. As -Xmx well as other related startup parameters. If the total amount of memory used by the JVM exceed the available physical memory, the operating system will use virtual memory.
Error message java.lang.OutOfMemoryError:? Out of swap space show, swap space (swap space, virtual memory) deficiency, is due to physical memory and swap space is insufficient resulting in memory allocation failure.
Cause Analysis
If the native heap memory is exhausted, memory allocation, JVM will throw java.lang.OutOfmemoryError:? Out of swap space error message, this message tells the user requesting the operation failed to allocate memory.
Java process uses virtual memory before the error occurred. For Java garbage collection , this is difficult to cope with the scene. Even modern GC algorithms very advanced, but the virtual memory swap system caused delays, make GC pause times swelled to intolerable proportions.
Often the cause of the operating system level results in java.lang.OutOfMemoryError:? Out of swap space problems, such as:
- Operating system swap space is too small.
- A process on the machine swallowed up all the memory resources.
Of course, memory leaks may also be a local application (native leak) caused by, for example, a program / library continue to apply local memory, not to be released.
solution
There are several solutions to this problem.
The first, and easiest way to increase the size of virtual memory (swap space) for each operating system setup methods are not the same, such as Linux, you can use the following command set:
swapoff -a
dd if=/dev/zero of=swapfile bs=1024 count=655360 mkswap swapfile swapon swapfile
Which creates a 640MB size of the swapfile (swap file) and enable the file.
Because the garbage collector to clean up the entire memory space, so the virtual memory for Java GC is unbearable. When there is memory swapping, perform garbage collection of pause time will increase a hundred times, or even more, so it is best not to increase virtual memory.
If the program also allows environmental interference "bad neighbor effect", the JVM and other programs also compete computing resources and improve performance is to deploy a separate way to a dedicated server / virtual machine.
Most of the time, the only thing we can do is upgrade the server configuration, adding memory physical machine. Of course, the program can be optimized to reduce the amount of memory space, which means can be detected / code assignment by a large amount of memory heap Dump Analyzer.
Original link: https://plumbr.eu/outofmemoryerror/out-of-swap-space
Translation Date: September 27, 2017
Translators: anchor: http://blog.csdn.net/renfufei