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What do 'real', 'user' and 'sys' mean in the output of time(1)?
... niters = strtoll(argv[1], NULL, 0);
} else {
niters = 1000000000;
}
if (argc > 2) {
nthreads = strtoll(argv[2], NULL, 0);
} else {
nthreads = 1;
}
threads = malloc(nthreads * sizeof(*threads));
thread_args = malloc(nthreads * sizeof(*thr...
How do I limit the number of rows returned by an Oracle query after ordering?
...37 seconds
Short alternative: 110-140 seconds
Selecting rows between 100,000 and 100,010:
AskTom: 60 seconds
Analytical: 100 seconds
Selecting rows between 9,000,000 and 9,000,010:
AskTom: 130 seconds
Analytical: 150 seconds
...
Convert Datetime column from UTC to local time in select statement
...ge to winter or summer time. For example
select cast('2017-02-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'
select cast('2017-08-08 09:00:00.000' as datetime) AT TIME ZONE 'Eastern Standard Time'
results:
2017-02-08 09:00:00.000 -05:00
2017-08-08 09:00:00.000 -04:00
You ca...
Parsing huge logfiles in Node.js - read in line-by-line
... by line using stream & pipe. For testing I used a 2.1 gb file with 17.000.000 records. Ram usage did not exceed 60 mb.
First, install the event-stream package:
npm install event-stream
Then:
var fs = require('fs')
, es = require('event-stream');
var lineNr = 0;
var s = fs.createReadS...
R memory management / cannot allocate vector of size n Mb
...o have a matrix of the training data (up to 60 bands) and anywhere from 20,000 to 6,000,000 rows to feed to randomForest. Currently, I max out at about 150,000 rows because I need a contiguous block to hold the resulting randomForest object... Which is also why bigmemory does not help, as randomFore...
一个故事告诉你比特币的原理及运作机制 - 创意 - 清泛网 - 专注C/C++及内核技术
...知道，如果编号的每一个数字都是随机的，那么平均写1000多张幸运数字不同的纸才能获得一个有效的编号。
这就奇怪了，这些矿工为什么要拼命干这看似无意义的事情呢？还记得之前说过矿工有报酬吧，这就是矿工的动力了。...
How do I declare a 2d array in C++ using new?
...tend to live in discontinuous parts of memory. One row may be at address 1,000, another at address 100,000—you get the idea. This means that when you're traversing the matrix, you're leaping through memory like a wild person. This tends to result in cache misses that vastly slow down your processi...
How does password salt help against a rainbow table attack?
...the purpose: let's say the attacker wants to build a rainbow table for 100,000 commonly used english words and typical passwords (think "secret"). Without salt she would have to precompute 100,000 hashes. Even with the traditional UNIX salt of 2 characters (each is one of 64 choices: [a–zA–Z0–...
What's the most efficient way to erase duplicates and sort a vector?
...
@Kyle: It's pretty large. I used datasets of 1,000,000 randomly drawn integers between 1 and 1000, 100, and 10 for this graph.
– Nate Kohl
Jun 26 '09 at 15:10
...
Does Django scale? [closed]
...21.4.2015) and 70 Million users in 2013
Bitbucket: 200TB of Code and 2.500.000 Users
Disqus: Serving 400 million people with Python.
curse.com: 600k daily visits.
tabblo.com: 44k daily visits, see Ned Batchelder's posts Infrastructure for modern web sites.
chesspark.com: Alexa rank about 179k.
pownc...