Why is CompareAndSwap instruction considered expensive?
I read in a book:
"Memory barriers are expensive, about as
expensive as an atomic compareAndSet()
instruction."
Thanks!
I'm building a little script that will connect to an IMAP account and grab the content of the email and also the attachments. It works well for the most part, but when a really large file comes in, it causes the script to time out. Is there any way that I can check the file size before trying to grab it? I think that would be the simplest solution. Otherwise, I may have to upgrade to a server that has more memory.
$fp_src=fopen('file','r');
$filter = stream_filter_prepend($fp_src, 'convert.iconv.ISO-8859-1/UTF-8');
while(fread($fp_src,4096)){
++$count;
if($count%1000==0) print ftell($fp_src)."\n";
}
When I run this the script ends up consuming ~ 200 MB of RAM after going through just 35MB of the file.
Running it without the stream_filter zips right through with a constant memory footprint of ~10 MB.
What gives?
I was doing some work handling a lot of information and my partner told me that I was using too many matrices to manipulate the variables of the problem. The idea was to use one dimension arrays int a[] instead of the 2 dimensional arrays int b[][], to save memory and processing speed of the algorithm. How certain is that this change will accelerate the speed of execution or compilation of my code in c ++?
Does closing a java.sql.Connection also close all the statements, prepared statements, etc. obtained from that connection? Or is there going to be memory leak if I close the connection but leave the statements, etc. unclosed?
Hi,
list<Dog*> dog;
.............
............
So I added many dog objects to it.
If I call dog.pop_front();
Does memory automatically gets deallocated ?
Hi,
I have a rdf file (file.trp) in n-triples format, where each line is:
"subject predicate object ."
I tried to use rdf_load in semweb/rdf_db to load it into memory, but failed. Here is what I tried:
?- rdf_load('file.trp').
?- rdf_load('file.trp', [format(triples]).
the manual says it supports xml and triples. But it only loads rdf xml files. How can I load such rdf triple file?
Thanks,
Li
I have a class definition of the form
class X
{
public:
//class functions
private:
A_type *A;
//other class variables
};
and struct A_type is defined as
struct A_type
{
string s1,s2,s3;
};
Inside the constructor, I allocate appropriate memory for A and try A[0].s1="somestring";
It shows segmentation fault.
Is this kind of declaration invalid, or am I missing something
As I remember there is a magic command line option in Java that turn on writing of operations that are currently executed to console. The output was looked like byte code. I do not mean -verbose, because it prints only class loading, while this option outputs information like memory allocation etc.
I have a huge problem with ElanTech touchpad. Without the ElanTech driver both the keys can be used at the same time(R+L). This is usefull in games like Mafia2 (can't play without it). When I install their driver I get the gestures, scrolling etc. but I can't use both keys at the same time. It is a common problem.
Acer Aspire v3-571G Windows 7 x64
This didn't work at all: Synaptics 15.3.41.5
Is there any universal driver which will give me at least scrolling and simultaneous keys usage?
Is is bad practice to pass the Context to a constructor and save it as a private variable for internal use? The other option is to pass the Context as a parameter to methods that need it.
Which is the better option?
I have a feeling that passing to the constructor might result in memory leaks accidentally.
I have some questions about singletons in C++.
Under what situations is a singleton a must?
What are the pros and cons of singletons? I was told they could cause memory leaks, how is that? I was also told that initialization is a problem, is that true?
Is there a more efficient way than using numpy.asarray() to generate an array from output in the form of a list?
This appears to be copying everything in memory, which doesn't seem like it would be that efficient with very large arrays.
(Updated) Example:
import numpy as np
a1 = np.array([1,2,3,4,5,6,7,8,9,10]) # pretend this has thousands of elements
a2 = np.array([3,7,8])
results = np.asarray([np.amax(np.where(a1 > element)) for element in a2])
I am sorting a hash in Perl. I encountered an Out of memory error when running my Perl Script:
foreach $key (sort (keys(%hash))) {
....
}
How do I sort a hash that has tons of data?
If I have a Facebook app, and my users agree to allow my app to access their information, photos, friends, etc, is it ethical to grab their information when they log in, and then saving it in memory so that the next time he goes to my app, it can load faster?
If so, what about when the user logged off? Is the right thing to do to is to delete all the cached information and photos that the user provided?
Has Facebook got any way to detect that we're doing this (saving their information, etc)?
I was wondering how Java sorts items in the Map (HashMap or Hashtable) when they are added. Are the keys sorted by the hashcode, memory reference or by allocation precedence...?
It's because I've noticed same pairs in the Map are not always sorted in the same order
c code
extern "C" __declspec(dllexport) int export(LPCTSTR inputFile, string &msg)
{
msg = "haha"
}
c# code
[DllImport("libXmlEncDll.dll")]
public static extern int XmlDecrypt(StringBuilder inputFile, ref Stringbuilder newMsg)
}
I got an error when I try to retrieve the content of newMsg saying that I'm trying to write to a protected memory area.
What is the best way to retrieve the string from c to c#. Thanks.
Hi, I have a structs action object instance that loads a variable from a properties file.I want it to happen only the first time the action is called, so in further executions its read from memory. Any hints ? Thanks.
I found OWSTIMER consume a lot of memory during create personal sites. (I have to pre-create personal sites for many users)
After googling I found some suggestion to restart OWSTIMER but it’ll grow up again after create several personal sites. So I have to restart OWSTIMER every hour.
Did you know any impact of restart OWSTIMER every hour?
Thank you
Hi,
I'm implementing a program which gets text from various sites and checks which ones are most relevant to a query. The problem is that when I have breakpoints in my code it works perfectly well but without it, the program just freezes. Is this a memory issue? What can I do to solve this please?
THanks
I used strtol to convert a string to hex, now I need to print it to the screen. I'm not sure if I can use sprintf since I only have 20k of memory to use on this board. Alternatives welcome.
I was looking at AppFog's Pricing and they appear to be giving 2GB of ram away for free, to nonpaying customers. This seems unprecedented for PAAS provodes--providers like Heroku and App Engine remove the app from memory if it has been inactive for certain amount of time. Does cloudfoundry work similarly? Am I wrong in assuming that in a few years appfog servers will be filled with inactive non paying applications?
I'm trying to use the OpenCA library in a C++ application. However, when including the file pki_x509_data_st.h the following code fragment is encountered:
typedef struct pki_x509_callbacks_st {
/* ---------------- Memory Management -------------------- */
void * (*new) (void );
void (*free) (void *x );
void * (*dup) (void *x );
This won't compile because of the "new" pointer declaration.
How can I make it work?