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Multithreading: What is the point of more threads than cores?
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The answer revolves around the purpose of threads, which is parallelism: to run several separate lines of execution at once. In an 'ideal' system, you would have one thread executing per core: no interruption. In reality this isn't the case. Even if you have four cores and four workin...
BLE（二）信道&数据包&协议栈格式 - 创客硬件开发 - 清泛IT社区，...
...一定频率范围下的频带资源（Frequency Band）；
BLE的市场定位是个体和民用，因此使用免费的ISM频段（频率范围是2.400-2.4835 GHz）；
为了同时支持多个设备，将整个频带分为40份，每份的带宽为2MHz，称作RF Channel。
所以经过上面...
Pandas aggregate count distinct
...aframe, then grouped to ~2M
%time _=g.agg({"id": lambda x: x.nunique()})
CPU times: user 3min 3s, sys: 2.94 s, total: 3min 6s
Wall time: 3min 20s
%time _=g.agg({"id": pd.Series.nunique})
CPU times: user 3min 2s, sys: 2.44 s, total: 3min 4s
Wall time: 3min 18s
%time _=g.agg({"id": "nunique"})
CPU...
How to turn off INFO logging in Spark?
I installed Spark using the AWS EC2 guide and I can launch the program fine using the bin/pyspark script to get to the spark prompt and can also do the Quick Start quide successfully.
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Queue.Queue vs. collections.deque
...nd collections.deque serve different purposes. Queue.Queue is intended for allowing different threads to communicate using queued messages/data, whereas collections.deque is simply intended as a datastructure. That's why Queue.Queue has methods like put_nowait(), get_nowait(), and join(), whereas co...
Command-line Tool to find Java Heap Size and Memory Used (Linux)?
...tion which options of jstat one should use in order to verify just the overall memory usage of a JVM? Let's say you start the JVM with Xms=4g and Xmx=4g and you want to see, how much memory of that is already used?
– basZero
Feb 5 '14 at 9:44
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What is the purpose of XORing a register with itself? [duplicate]
...ad dependency on eax, so the execution time is the same" The processor actually does even better: it just executes a register rename internally, and doesn't even do anything at all with eax.
– kquinn
Sep 8 '09 at 22:16
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正则表达式 30 分钟入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...,所以本页排版比较混乱,推荐你到原处查看,看完了如果有问题,再到这里来提出.
一些要说的话：
如果你没有正则表达式的基础，请跟着教程“一步步来”。请不要大概地扫两眼就说看不懂——以这种态度我写成什么样你也看...
Why does the order of the loops affect performance when iterating over a 2D array?
... x[1][0] etc...
Meaning that you're hitting them all in order. Now look at the 1st version. You're doing:
x[0][0]
x[1][0]
x[2][0]
x[0][1]
...
How to keep the console window open in Visual C++?
...ause") or any other garbage. Changing this works.
– Callat
Apr 22 '16 at 16:08
Ctrl+F5 means 'Start Without Debugging'...