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Why is creating a Thread said to be expensive?
...tem calls need to be made to create / register the native thread with the host OS.
Descriptors need to be created, initialized and added to JVM-internal data structures.
It is also expensive in the sense that the thread ties down resources as long as it is alive; e.g. the thread stack, any objects...
How can I tell if I'm running in 64-bit JVM or 32-bit JVM (from within a program)?
...the bitness of this JVM with:
System.getProperty("sun.arch.data.model");
Possible results are:
"32" – 32-bit JVM
"64" – 64-bit JVM
"unknown" – Unknown JVM
As described in the HotSpot FAQ:
When writing Java code, how do I distinguish between 32 and 64-bit operation?
There's no public API th...
How to create full compressed tar file using Python?
... a .tar.gz (aka .tgz) for an entire directory tree:
import tarfile
import os.path
def make_tarfile(output_filename, source_dir):
with tarfile.open(output_filename, "w:gz") as tar:
tar.add(source_dir, arcname=os.path.basename(source_dir))
This will create a gzipped tar archive contain...
Find duplicate lines in a file and count how many time each line was duplicated?
...iq -c | grep -v '^ *1 '
For the given example, the result would be:
3 123
2 234
If you want to print counts for all lines including those that appear only once:
sort FILE | uniq -c
or, with GNU long options (on Linux):
sort FILE | uniq --count
For the given input, the output is:
...
How to get current CPU and RAM usage in Python?
...e ps, top and Windows task manager.
It currently supports Linux, Windows, OSX, Sun Solaris, FreeBSD, OpenBSD and NetBSD, both 32-bit and 64-bit architectures, with Python versions from 2.6 to 3.5 (users of Python 2.4 and 2.5 may use 2.1.3 version).
Some examples:
#!/usr/bin/env python
import psut...
How do you remove all the options of a select box and then add one option and select it with jQuery?
.../attr/text like: .append($("<option></option>").attr("value", '123').text('ABC!')
– Brock Hensley
Jun 27 '13 at 21:58
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Can I change the height of an image in CSS :before/:after pseudo-elements?
...nswered Jan 23 '12 at 21:39
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How can I install Apache Ant on Mac OS X?
...
Ant is already installed on some older versions of Mac OS X, so you should run ant -version to test if it is installed before attempting to install it.
If it is not already installed, then your best bet is to install Homebrew (brew install ant) or MacPorts (sudo port install ap...
How can I change Mac OS's default Java VM returned from /usr/libexec/java_home
...dkhome="`/usr/libexec/java_home -v '1.7*'`"
and this will force it to choose Java 7 instead of 8.
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How do you normalize a file path in Bash?
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For those of you what need a OS X solution, check out Adam Liss' answer below.
– Trenton
May 22 '16 at 6:16
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