大约有 2,193 项符合查询结果（耗时：0.0095秒） [XML]
Amazon EC2, mysql aborting start because InnoDB: mmap (x bytes) failed; errno 12
...e enough (512M) memory for the InnoDB buffer pool:
Fatal error: cannot allocate memory for the buffer pool
That begs three questions:
How much memory is on your instance? Should there be enough memory to accommodate the 512M InnoDB is trying to grab for the buffer pool, plus everything else...
What is the “Execute Around” idiom?
...e you write a method to do things which are always required, e.g. resource allocation and clean-up, and make the caller pass in "what we want to do with the resource". For example:
public interface InputStreamAction
{
void useStream(InputStream stream) throws IOException;
}
// Somewhere else ...
iOS: How to get a proper Month name from a number?
...nt monthNumber = 11; //November
NSDateFormatter *df = [[[NSDateFormatter alloc] init] autorelease];
NSString *monthName = [[df monthSymbols] objectAtIndex:(monthNumber-1)];
Note that you'll need to subtract 1 from your 1..12 monthNumber since monthSymbols is zero-based.
...
String concatenation: concat() vs “+” operator
...then throwing it away when you create the final String. In practice memory allocation is surprisingly fast.
Update: As Pawel Adamski notes, performance has changed in more recent HotSpot. javac still produces exactly the same code, but the bytecode compiler cheats. Simple testing entirely fails bec...
Determine the number of lines within a text file
...ne loads the entire contents of the file into an array which means it must allocate at least as much memory as the size of the file. The second merely loops one line at a time so it never has to allocate more than one line's worth of memory at a time. This isn't that important for small files, but f...
Explain the concept of a stack frame in a nutshell
...rocessor knows anything about stack, because WE manipulate it via subbing (allocation), pushing and popping. And so here are calling conventions which explain how we should use the stack.
– Victor Polevoy
Apr 18 '18 at 7:18
...
What does the “__block” keyword mean?
...and static.[testme] Variables qualified by __block act as if they were in allocated storage and this storage is automatically recovered after last use of said variable. An implementation may choose an optimization where the storage is initially automatic and only "moved" to allocated (heap) storag...
What do the plus and minus signs mean in Objective-C next to a method?
...se?
[CustomClass classMethod];
CustomClass *classObject = [[CustomClass alloc] init];
[classObject instanceMethod];
share
|
improve this answer
|
follow
|
...
Shards and replicas in Elasticsearch
...search performance and for fail-over. A replica shard is never going to be allocated on the same node where the related primary is (it would pretty much be like putting a backup on the same disk as the original data).
Back to our example, with 1 replica we'll have the whole index on each node, sinc...
Why was “Avoid Enums Where You Only Need Ints” removed from Android's performance tips?
...
TLDR: Dalvik was not good with memory allocation and Enum uses more memory than int. Android Lollipop replaced Dalvik with ART which does not suffer from the same limitations. Thus this recommendation is not relevant anymore.
The long answer:
Wow! 8 years, 5 a...