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Performance optimization strategies of last resort [closed]
...y under a broad range of scenarios, and perform null checks on parameters, etc. By re-implementing a method you may be able to strip out a lot of logic that does not apply in the exact circumstance you are using it.
Down-sides: writing additional code means more surface area for bugs.
Do use library...
Is SHA-1 secure for password storage?
... systems do: the hashed passwords, which used to be in the world-readable /etc/password file, are now in the /etc/shadow file which is protected against read access, except by a few privileged applications. The assumption here is that if the attacker can read /etc/shadow, then he probably has enough...
How to Calculate Execution Time of a Code Snippet in C++
...
I have another working example that uses microseconds (UNIX, POSIX, etc).
#include <sys/time.h>
typedef unsigned long long timestamp_t;
static timestamp_t
get_timestamp ()
{
struct timeval now;
gettimeofday (&now, NULL);
return now.tv_usec + ...
python-pandas and databases like mysql
...SQLdb.connect(host='myhost',
port=3306,user='myusername', passwd='mypassword',
db='information_schema')
df_mysql = pd.read_sql('select * from VIEWS;', con=mysql_cn)
print 'loaded dataframe from MySQL. records:', len(df_mysql)
mysql_cn.close()
...
How to export and import a .sql file from command line with options? [duplicate]
... check and confirm: grant all privileges on *.* to root@"%" identified by "Passwd";
ERROR 2006 (HY000) at line 866: MySQL server has gone away
mysqldump: Got errno 32 on write
# set this values big enough on destination mysql server, like: max_allowed_packet=1024*1024*20
# use compress parameter ...
Why is reading lines from stdin much slower in C++ than Python?
...lly timing the execution of cat, not your benchmark. The 'user' and 'sys' CPU usage displayed by time are those of cat, not your benchmarked program. Even worse, the 'real' time is also not necessarily accurate. Depending on the implementation of cat and of pipelines in your local OS, it is possib...
deque iterator not dereferencable 问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
deque iterator not dereferencable 问题STL里面出现这个问题，纠结了半天，不知道什么原因。当然deque iterator not dereferencable。这个是deque出问题，vector、list也可以出...STL里面出现这个问题，纠结了半天，不知道什么原因。
当然deque iterat...
怎么解决MQTT连接掉线，自动连接问题，同时解决，反复断开连接，断开连接问...
解决MQTT退出后台后掉线自动连接问题，现在可以实现自动连接，但是在返回控制界面的时候，反复断开反复链接，还有切换页面的时候返回也是同样的问题，还有连接一个服务器，需要每个页面单独设置MQTT连接吗，是不是可以...
What is “vectorization”?
...GE
Vectorization describes the absence of any explicit looping, indexing, etc., in the code - these things are taking place, of course, just “behind the scenes” in optimized, pre-compiled C code. Vectorized code has many advantages, among which are:
vectorized code is more concise and easier ...
How do I get Windows to go as fast as Linux for compiling C++?
...is by looking at the differences between the two compilers, build systems, etc etc.
– surfasb
Dec 20 '11 at 1:24
Windo...