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内存优化总结:ptmalloc、tcmalloc和jemalloc - 操作系统(内核) - 清泛网 - ...
...内存到CentralCache里。 解决了ptmalloc2中arena之间不能迁移的问题。
Tcmalloc占用更少的额外空间。例如，分配N个8字节对象可能要使用大约8N * 1.01字节的空间。即，多用百分之一的空间。Ptmalloc2使用最少8字节描述一个chunk。
更快。...
LINQ To Entities does not recognize the method Last. Really?
...u pointed out, it could bring back thousands of records and waste loads of CPU materialising objects that will never get used)
Again, I would not recommend doing this second, but it does help illustrate the difference between where and when the LINQ expression is executed.
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unsigned int vs. size_t
...2 (byte). 16 bit arithmetic was faster than 32 bit arithmetic, though the CPU could handle a (logical) memory space of up to 4 GiB.
Use the int type only when you care about efficiency as its actual precision depends strongly on both compiler options and machine architecture. In particular the C ...
What's the difference between Task.Start/Wait and Async/Await?
...e another thread is doing the work, and that thread has been assigned to a CPU, so the work is actually being done. Maybe the work is being done by hardware and there is no thread at all. But surely, you say, there must be some thread in the hardware. No. Hardware exists below the level of thread...
Grepping a huge file (80GB) any way to speed it up?
...
If you have a multicore CPU, I would really recommend GNU parallel. To grep a big file in parallel use:
< eightygigsfile.sql parallel --pipe grep -i -C 5 'db_pd.Clients'
Depending on your disks and CPUs it may be faster to read larger blocks:
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How do I create a unique constraint that also allows nulls?
...onal disk space.
Note that if you don't want an index, you can still save CPU by making the expression be precalculated to disk by adding the keyword PERSISTED to the end of the column expression definition.
In SQL Server 2008 and up, definitely use the filtered solution instead if you possibly ca...
Should I instantiate instance variables on declaration or in the constructor?
...ow it was him). Personal taste is personal taste; ultimately, neither the CPU nor the JRE care about syntactical style.
– Aquarelle
Sep 20 '13 at 22:38
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How do I automatically update a timestamp in PostgreSQL
... Says so in the Postgres documentation of the types. Varchar has extra CPU cycles to check for the constraint, which doesn't happen on TEXT.
– Rahly
Jun 21 '17 at 15:50
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How to destroy an object?
...for "speed", but if you want to reclaim memory immediately (at the cost of CPU) should want to use null.
Like others mentioned, setting to null doesn't mean everything is reclaimed, you can have shared memory (uncloned) objects that will prevent destruction of the object. Moreover, like others h...
What is non-blocking or asynchronous I/O in Node.js?
...ng, asynchronous operations is that you can maximize the usage of a single CPU as well as memory.
Synchronous, blocking example
An example of synchronous, blocking operations is how some web servers like ones in Java or PHP handle IO or network requests. If your code reads from a file or the datab...