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  • CPU load, USB connection vs. NIC

    - by T.J. Crowder
    In general, and understanding the answer may vary by manufacturer and model (and driver, and...), in consumer-grade workstations with integrated NICs, does the NIC rely on the CPU for a lot of help (as is typically the case with a USB controller, for instance), or is it fairly intelligent and capable on its own (like, say, the typical Firewire controller)? Or is the question too general to answer? (If it matters, you can assume Linux.) Background: I'm looking at connecting a device (digital television capture) that will be delivering ~20-50 Mbit/sec of data to a somewhat under-powered workstation. I can get a USB 2 High-speed device, or a network-attached device, and am interested in avoiding impacting the CPU where possible. Obviously, if it's a 100Mbit NIC, that's roughly half its theoretical inbound bandwidth, whereas it's only roughly a tenth of the 480 Mbit/second the USB 2 "High Speed" interface. But if the latter requires a lot of CPU support and the former doesn't...

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  • Can KVM CPU assignment count differ from physical hosts CPU count?

    - by javano
    I have read this question. I knew already that I could for example, have a quad core machine with four guests each having two vCPUs. As they don't all be require 100% CPU usage all the time, the scheduler would handle this for me. My question is about how this relates to a fail-over or migration situation; If host1 has two dual-core CPUs, and I assign guest1 four vCPUs (so it accessed all four physical cores), what will happen if I try and migrate it to host2 which only has one dual-core CPU? Can qemu-kvm emulate more vCPUs than there are physical? Or would I have to shut down the virtual machine, change the CPU assignment, migrate it, and then boot it back up (so no live migration)? Many thanks.

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  • ganglia graphs like munin for cpu, etc?

    - by CarpeNoctem
    I'm coming from munin and a CPU graph contains data for system, user, nice, etc ALL on one graph. I just installed ganglia and setup the basic monitoring. It appears that each type of cpu data is a separate graph! WTF is this and can I change the defaults to combine these into a single per host? That is my question, how do I combine cpu data into a single graph. Also, can I change the layout to something closer to munin's day-week side-by-side layout? I'm trying to be impartial and give ganglia a chance. ;)

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  • VPS hang when one Virtual CPU usage is 100%

    - by garconcn
    We are using Xen Center to manage all of our cPanel VPS servers. The hardware has two CPUs(Intel(R) Xeon(R) CPU [email protected]) and 32GB memory. Each hardware has 4 cPanel VPS and each VPS has 8GB memory and 4 Virtual CPUS. Every one or two months, one of the VPS server will hang because one Virtual CPU usage is 100% and it couldn't release the CPU unless we use force reboot. We have 10 similar hardware, and this cause our server down almost every day. We have tried to avoid the Statistics Processing and Fantastico update during the night, but the problem still happens randomly. I can not find anything in the server log when it hangs. Any clue? Thank you.

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  • Cherokee high virtual memory usage even after disabling I/O Cache

    - by nidheeshdas
    I've Ubuntu 10.04LTS 64-bit running on a openvz container and Cherokee 1.0.8 compiled from source. The virtual memory usage of cherokee-worker is around 430 MB even after disabling I/O cache from Advanced - I/O Cache - NOT enabled. Is this issue particular to openvz? Because many people reported to have successfully reduced virt memory usage by disabling io cache. htop output: http://imgur.com/z5JEL.jpg (newbies not allowed to post image.) thanks in advance. nidheeshdas

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  • APC has no system cache entries

    - by lazzio
    I have 2 web servers to provide PHP websites. One server is : Apache + PHP-FPM + APC The other : Apache with MPM-itk + APC. For both of these servers, APC has no cache system entries but only users cache entries as you can see on the screenshot. APC with only users cache entries APC configuration is : apc.cache_by_default 1 apc.canonicalize 1 apc.coredump_unmap 0 apc.enable_cli 0 apc.enabled 1 apc.file_md5 0 apc.file_update_protection 2 apc.filters apc.gc_ttl 3600 apc.include_once_override 0 apc.lazy_classes 0 apc.lazy_functions 0 apc.max_file_size 2 apc.mmap_file_mask apc.num_files_hint 1000 apc.preload_path apc.report_autofilter 0 apc.rfc1867 0 apc.rfc1867_freq 0 apc.rfc1867_name APC_UPLOAD_PROGRESS apc.rfc1867_prefix upload_ apc.rfc1867_ttl 3600 apc.shm_segments 1 apc.shm_size 256 apc.stat 1 apc.stat_ctime 0 apc.ttl 7200 apc.use_request_time 1 apc.user_entries_hint 4096 apc.user_ttl 7200 apc.write_lock 1 Does anyone know why APC acts like this and how to make it work well ? Thank you for your help!

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  • Graphing/charting of CPU utilisation [on hold]

    - by Peter
    So nagios can be good at graphing particular resource utilisation or other metrics, but I'm looking for a tool that can output a chart or other graphical representation of how much CPU time/CPU utilisation /all/ services on a server are currently consuming. I think New Relic could probably achieve this to an extent, but I was wondering if there was a popular open source app used for this. In case I am explaining this in a bad way, my actual problem is that I have a shared server with suexec enabled (ie. httpd cgi running under multiple user accounts). I'd like to know which users are using the most CPU during periods of the day.

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  • Windows 2008 R2 on ESXi 4.1 cpu utilization kernel high

    - by MK.
    I have a Win2k8 guest running on ESXi 4.1. The host has 12 cores and the problem happens even if the guest is the only VM on the host. We have 4 cores dedicated to the guest. We noticed that network starts chocking when the CPU load goes up. After some testing we noticed that when running a simple CPU hogging tool set up to run 3 threads at 100% the regular CPU load goes to 75% like it should and the "kernel times" graph in task manager goes up to 25%. My intuition tells me that the network problem and kernel times problem are the same. This is confirmed by another similar VM we created on the same host which doesn't have either of the problems. VMWare tools are obviously installed. The nic is e1000. What else can we do to troubleshoot this?

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  • Cherokee high virtual memory usage even after disabling I/O Cache

    - by nidheeshdas
    hi all I've Ubuntu 10.04LTS 64-bit running on a openvz container and Cherokee 1.0.8 compiled from source. The virtual memory usage of cherokee-worker is around 430 MB even after disabling I/O cache from Advanced - I/O Cache - NOT enabled. Is this issue particular to openvz? Because many people reported to have successfully reduced virt memory usage by disabling io cache. htop output: http://imgur.com/z5JEL.jpg (newbies not allowed to post image.) thanks in advance. nidheeshdas

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  • iTunes high CPU usage

    - by Calm Storm
    I upgraded to iTunes 10.4.1 and use Windows 7 and my itunes library is not that large at all (say about 20gb) When I start iTunes the CPU goes between 60-80% and stays there for a long time. I see that the itunes.exe takes about 70% of CPU in Process Explorer and it spawns a SearchProtocolHost.exe every 2 mins or so which takes < 0.1% CPU. Other than that iTunes.exe is always at 70-90% and never lets me do anything else. Does someone have a suggestion? EDIT: I have tried reinstalling 10.4.1 completely deleting my library and starting with a plain installation and that does not work I have tried downgrading to 10.3.x and that does not work either :(

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  • No improvement in speed when using Ehcache with Hibernate

    - by paddydub
    I'm getting no improvement in speed when using Ehcache with Hibernate Here are the results I get when i run the test below. The test is reading 80 Stop objects and then the same 80 Stop objects again using the cache. On the second read it is hitting the cache, but there is no improvement in speed. Any idea's on what I'm doing wrong? Speed Test: First Read: Reading stops 1-80 : 288ms Second Read: Reading stops 1-80 : 275ms Cache Info: elementsInMemory: 79 elementsInMemoryStore: 79 elementsInDiskStore: 0 JunitCacheTest public class JunitCacheTest extends TestCase { static Cache stopCache; public void testCache() { ApplicationContext context = new ClassPathXmlApplicationContext("beans-hibernate.xml"); StopDao stopDao = (StopDao) context.getBean("stopDao"); CacheManager manager = new CacheManager(); stopCache = (Cache) manager.getCache("ie.dataStructure.Stop.Stop"); //First Read for (int i=1; i<80;i++) { Stop toStop = stopDao.findById(i); } //Second Read for (int i=1; i<80;i++) { Stop toStop = stopDao.findById(i); } System.out.println("elementsInMemory " + stopCache.getSize()); System.out.println("elementsInMemoryStore " + stopCache.getMemoryStoreSize()); System.out.println("elementsInDiskStore " + stopCache.getDiskStoreSize()); } public static Cache getStopCache() { return stopCache; } } HibernateStopDao @Repository("stopDao") public class HibernateStopDao implements StopDao { private SessionFactory sessionFactory; @Transactional(readOnly = true) public Stop findById(int stopId) { Cache stopCache = JunitCacheTest.getStopCache(); Element cacheResult = stopCache.get(stopId); if (cacheResult != null){ return (Stop) cacheResult.getValue(); } else{ Stop result =(Stop) sessionFactory.getCurrentSession().get(Stop.class, stopId); Element element = new Element(result.getStopID(),result); stopCache.put(element); return result; } } } ehcache.xml <cache name="ie.dataStructure.Stop.Stop" maxElementsInMemory="1000" eternal="false" timeToIdleSeconds="5200" timeToLiveSeconds="5200" overflowToDisk="true"> </cache> stop.hbm.xml <class name="ie.dataStructure.Stop.Stop" table="stops" catalog="hibernate3" mutable="false" > <cache usage="read-only"/> <comment></comment> <id name="stopID" type="int"> <column name="STOPID" /> <generator class="assigned" /> </id> <property name="coordinateID" type="int"> <column name="COORDINATEID" not-null="true"> <comment></comment> </column> </property> <property name="routeID" type="int"> <column name="ROUTEID" not-null="true"> <comment></comment> </column> </property> </class> Stop public class Stop implements Comparable<Stop>, Serializable { private static final long serialVersionUID = 7823769092342311103L; private Integer stopID; private int routeID; private int coordinateID; }

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  • Why does this Java code not utilize all CPU cores?

    - by ReneS
    The attached simple Java code should load all available cpu core when starting it with the right parameters. So for instance, you start it with java VMTest 8 int 0 and it will start 8 threads that do nothing else than looping and adding 2 to an integer. Something that runs in registers and not even allocates new memory. The problem we are facing now is, that we do not get a 24 core machine loaded (AMD 2 sockets with 12 cores each), when running this simple program (with 24 threads of course). Similar things happen with 2 programs each 12 threads or smaller machines. So our suspicion is that the JVM (Sun JDK 6u20 on Linux x64) does not scale well. Did anyone see similar things or has the ability to run it and report whether or not it runs well on his/her machine (= 8 cores only please)? Ideas? I tried that on Amazon EC2 with 8 cores too, but the virtual machine seems to run different from a real box, so the loading behaves totally strange. package com.test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; public class VMTest { public class IntTask implements Runnable { @Override public void run() { int i = 0; while (true) { i = i + 2; } } } public class StringTask implements Runnable { @Override public void run() { int i = 0; String s; while (true) { i++; s = "s" + Integer.valueOf(i); } } } public class ArrayTask implements Runnable { private final int size; public ArrayTask(int size) { this.size = size; } @Override public void run() { int i = 0; String[] s; while (true) { i++; s = new String[size]; } } } public void doIt(String[] args) throws InterruptedException { final String command = args[1].trim(); ExecutorService executor = Executors.newFixedThreadPool(Integer.valueOf(args[0])); for (int i = 0; i < Integer.valueOf(args[0]); i++) { Runnable runnable = null; if (command.equalsIgnoreCase("int")) { runnable = new IntTask(); } else if (command.equalsIgnoreCase("string")) { runnable = new StringTask(); } Future<?> submit = executor.submit(runnable); } executor.awaitTermination(1, TimeUnit.HOURS); } public static void main(String[] args) throws InterruptedException { if (args.length < 3) { System.err.println("Usage: VMTest threadCount taskDef size"); System.err.println("threadCount: Number 1..n"); System.err.println("taskDef: int string array"); System.err.println("size: size of memory allocation for array, "); System.exit(-1); } new VMTest().doIt(args); } }

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  • Is there a way to ignore Cache errors in Django?

    - by Josh Smeaton
    I've just set our development Django site to use redis for a cache backend and it was all working fine. I brought down redis to see what would happen, and sure enough Django 404's due to cache backend behaviour. Either the Connection was refused, or various other errors. Is there any way to instruct Django to ignore Cache errors, and continue processing the normal way? It seems weird that caching is a performance optimization, but can bring down an entire site if it fails. I tried to write a wrapper around the backend like so: class CacheClass(redis_backend.CacheClass): """ Wraps the desired Cache, and falls back to global_settings default on init failure """ def __init__(self, server, params): try: super(CacheClass, self).__init__(server, params) except Exception: from django.core import cache as _ _.cache = _.get_cache('locmem://') But that won't work, since I'm trying to set the cache type in the call that sets the cache type. It's all a very big mess. So, is there any easy way to swallow cache errors? Or to set the default cache backend on failure?

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  • prototype.js equivalent to jquery ajaxSettings cache = true addthis plugin

    - by openstepmedia
    I need help from a prototype.js expert: I'm trying to achieve the following (taken from the addthis forum), and port the solution from jquery to prototype.js (I'm using magento). Original post is here: http://www.addthis.com/forum/viewtopic.php?f=3&t=22217 For the getScript() function, I can create a custom function to load the remote js, however I'm trying to load the js file via the prototype ajax call, and trying to avoid having the script cached in the browser. <script type="text/javascript" src="http://code.jquery.com/jquery-latest.js"></script> <script type="text/javascript"> $(document).ready(function() { $("#changeURL").click(function() { $(".addthis_button").attr("addthis:url","http://www.example.com"); window.addthis.ost = 0; window.addthis.ready(); }); }); // prevent jQuery from appending cache busting string to the end of the URL var cache = jQuery.ajaxSettings.cache; jQuery.ajaxSettings.cache = true; jQuery.getScript('http://s7.addthis.com/js/250/addthis_widget.js'); // Restore jQuery caching setting jQuery.ajaxSettings.cache = cache; </script> <p id="changeURL">Change URL</p> <a class="addthis_button" addthis:url="http://www.google.com"></a> <script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#username=rahf"></script>

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  • How CPU finds ISR and distinguishes between devices

    - by ripunjay-tripathi-gmail-com
    I should first share all what I know - and that is complete chaos. There are several different questions on the topic, so please don't get irritated :). 1) To find an ISR, CPU is provided with a interrupt number. In x86 machines (286/386 and above) there is a IVT with ISRs in it; each entry of 4 bytes in size. So we need to multiply interrupt number by 4 to find the ISR. So first bunch of questions is - I am completely confused in mechanism of CPU receiving the interrupt. To raise an interrupt, firstly device shall probe for IRQ - then what ? The interrupt number travels "on IRQ" towards CPU? I also read something like device putting ISR address on data bus ; whats that then ? What is the concept of devices overriding the ISR. Can somebody tell me few example devices where CPU polls for interrupts? And where does it finds ISR for them ? 2) If two devices share an IRQ (which is very much possible), how does CPU differs amongst them ? What if both devices raise an interrupt of same priority simultaneously. I got to know there will be masking of same type and low priority interrupts - but how this communication happens between CPU and device controller? I studied the role of PIC and APIC for this problem, but could not understand. Thanks for reading. Thank you very much for answering.

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  • Why does Hibernate 2nd level cache only cache within a session?

    - by Synesso
    Using a named query in our application and with ehcache as the provider, it seems that the query results are tied to the session. Any attempt to access the value from the cache for a second time results in a LazyInitializationException We have set lazy=true for the following mapping because this object is also used by another part of the system which does not require the reference... and we want to keep it lean. <class name="domain.ReferenceAdPoint" table="ad_point" mutable="false" lazy="false"> <cache usage="read-only"/> <id name="code" type="long" column="ad_point_id"> <generator class="assigned" /> </id> <property name="name" column="ad_point_description" type="string"/> <set name="synonyms" table="ad_point_synonym" cascade="all-delete-orphan" lazy="true"> <cache usage="read-only"/> <key column="ad_point_id" /> <element type="string" column="synonym_description" /> </set> </class> <query name="find.adpoints.by.heading">from ReferenceAdPoint adpoint left outer join fetch adpoint.synonyms where adpoint.adPointField.headingCode = ?</query> Here's a snippet from our hibernate.cfg.xml <property name="hibernate.cache.provider_class">net.sf.ehcache.hibernate.SingletonEhCacheProvider</property> <property name="hibernate.cache.use_query_cache">true</property> It doesn't seem to make sense that the cache would be constrained to the session. Why are the cached queries not usable outside of the (relatively short-lived) sessions?

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  • How to implement web cache: internal fragmentation VS external fragmentation

    - by Summer_More_More_Tea
    Hi there: I come up with this question when play with Firefox web cache: in which approach does the browser cache a response in limited disk space(take my configuration as an example, 50MB is the upper bound)? I think two ways can be employed. One is cache the total response object one by one, but this is inefficient and will introduce external fragmentation, thus the total cache space may not be fully used. The second is take the total space(50MB) as a consecutive file, splitting it into fixed-length slots; incoming response objects will also be treated blocks of data with the same length as the slots. We can fill slots until the whole file is run out of, then some displacement algorithm can be used to swap out the old cached objects. The latter approach will of course bing in internal fragmentation, but in my opinion is easier to implement and maintain than the first strategy. But when I enter Firefox's Cache directory, I find it (maybe) use a different method: a lot of varied-length files reside in that directory and all those files are filled with undisplayable characters. I don't but really want to know what mechanism that a commercial browser, e.g. Firefoix, employed to implement web cache. Regards.

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  • ASP.NET retrieve Average CPU Usage

    - by Sam
    Last night I did a load test on a site. I found that one of my shared caches is a bottleneck. I'm using a ReaderWriterLockSlim to control the updates of the data. Unfortunately at one point there are ~200 requests trying to update the data at approximately the same time. This also coincided with CPU usage spikes. The data being updated is in the ASP.NET Cache. What I'd like to do is if the CPU usage is around 75%, I'd like to just skip the cache and hit the database on another machine. My problem is that I don't know how expensive it is to create a new performance counter to check the cpu usage. Also, if I would probably like the average cpu usage over the last 2 or 3 seconds. However, I can't sit there and calculate the cpu time as that would take longer than it's taking to update the cache currently. Is there an easy way to get the average CPU usage? Are there any drawbacks to this? I'm also considering totaling the wait count for the lock and then at a certain threshold switch over to the database. The concern I had with this approach would be that changing hardware might allow more locks with less of a strain on the system. And also finding the right balance for the threshold would be cumbersome and it doesn't take into account any other load on the machine. But it's a simple approach, and simple is 99% of the time better.

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  • SelectQuery eating up 100% CPU

    - by modernzombie
    I am doing a query for all the users on the machine and when it executes it grabs 100% CPU and locks up the system. I have waited up to 5 minutes and nothing happens. In the Task Manager wmiprvse.exe is using all the CPU. When I kill that process everything returns to normal. Here is my code: SelectQuery query = new SelectQuery("Win32_UserAccount", "LocalAccount=1 and Domain='" + GetMachine().DomainName + "'"); using(ManagementObjectSearcher searcher = new ManagementObjectSearcher(query)) { IList<WindowsUser> users = new List<WindowsUser>(); Console.WriteLine("Getting users..."); foreach (ManagementObject envVar in searcher.Get()) { Console.WriteLine("Getting " + envVar["Name"].ToString() + "..."); } } In the console all I see is Getting users... and nothing else. The problem appears to be with searcher.Get(). Does anyone know why this query is taking 100% CPU? Thanks. EDIT: OK I found that it the WMI process is only eating 25% CPU but it doesn't get released if I end the program (the query never finishes). The next time I start an instance the process goes up to 50% CPU, etc, etc until it is at 100%. So my new question is why is the CPU not getting released and how long should a query like this take to complete?

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  • dpkg: error processing /var/cache/apt/archives/python2.6-minimal_2.6.6-5ubuntu1_i386.deb (--unpack)

    - by udo
    I had an issue (Question 199582) which was resolved. Unfortunately I am stuck at this point now. Running root@X100e:/var/cache/apt/archives# apt-get dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Done The following NEW packages will be installed: file libexpat1 libmagic1 libreadline6 libsqlite3-0 mime-support python python-minimal python2.6 python2.6-minimal readline-common 0 upgraded, 11 newly installed, 0 to remove and 0 not upgraded. Need to get 0B/5,204kB of archives. After this operation, 19.7MB of additional disk space will be used. Do you want to continue [Y/n]? Y (Reading database ... 6108 files and directories currently installed.) Unpacking python2.6-minimal (from .../python2.6-minimal_2.6.6-5ubuntu1_i386.deb) ... new installation of python2.6-minimal; /usr/lib/python2.6/site-packages is a directory which is expected a symlink to /usr/local/lib/python2.6/dist-packages. please find the package shipping files in /usr/lib/python2.6/site-packages and file a bug report to ship these in /usr/lib/python2.6/dist-packages instead aborting installation of python2.6-minimal dpkg: error processing /var/cache/apt/archives/python2.6-minimal_2.6.6-5ubuntu1_i386.deb (--unpack): subprocess new pre-installation script returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/python2.6-minimal_2.6.6-5ubuntu1_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1) results in above error. Running root@X100e:/var/cache/apt/archives# dpkg -i python2.6-minimal_2.6.6-5ubuntu1_i386.deb (Reading database ... 6108 files and directories currently installed.) Unpacking python2.6-minimal (from python2.6-minimal_2.6.6-5ubuntu1_i386.deb) ... new installation of python2.6-minimal; /usr/lib/python2.6/site-packages is a directory which is expected a symlink to /usr/local/lib/python2.6/dist-packages. please find the package shipping files in /usr/lib/python2.6/site-packages and file a bug report to ship these in /usr/lib/python2.6/dist-packages instead aborting installation of python2.6-minimal dpkg: error processing python2.6-minimal_2.6.6-5ubuntu1_i386.deb (--install): subprocess new pre-installation script returned error exit status 1 Errors were encountered while processing: python2.6-minimal_2.6.6-5ubuntu1_i386.deb results in above error. Running root@X100e:/var/cache/apt/archives# dpkg -i --force-depends python2.6-minimal_2.6.6-5ubuntu1_i386.deb (Reading database ... 6108 files and directories currently installed.) Unpacking python2.6-minimal (from python2.6-minimal_2.6.6-5ubuntu1_i386.deb) ... new installation of python2.6-minimal; /usr/lib/python2.6/site-packages is a directory which is expected a symlink to /usr/local/lib/python2.6/dist-packages. please find the package shipping files in /usr/lib/python2.6/site-packages and file a bug report to ship these in /usr/lib/python2.6/dist-packages instead aborting installation of python2.6-minimal dpkg: error processing python2.6-minimal_2.6.6-5ubuntu1_i386.deb (--install): subprocess new pre-installation script returned error exit status 1 Errors were encountered while processing: python2.6-minimal_2.6.6-5ubuntu1_i386.deb is not able to fix this. Any clues how to fix this?

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  • Why doesn't Firefox redownload images already on a page?

    - by vvo
    Hello, i just read this article : https://developer.mozilla.org/en/HTTP_Caching_FAQ There's a firefox behavior (and some other browsers i guess) i'd like to understand : if i take any webpage and try to insert the same image multiple times in javascript, the image is only downloaded ONCE even if i specifiy all needed headers to say "do no ever use cache". (see article) I know there are workarounds (like addind query strings to end of urls etc) but why do firefox act like that, if i say that an image do not have to be cached, why is the image still taken from cache when i try to re-insert it ? Plus, what cache is used for this ? (I guess it's the memory cache) Is this behavior the same for dynamic inclusion for example ? ANSWSER IS NO :) I just tested it and the same headers for a js script will make firefox redownload it each time you append the script to the DOM. PS: I know you're wondering WHY i need to do that (appending same image multiple times and force to redownload but this is the way our app works) thank you The good answer is : firefox will store images for the current page load in the memory cache even if you specify he doesnt have to cache them. You can't change this behavior but this is odd because it's not the same for javascript files for example Could someone explain or link to a document describing how firefox cache WORKS?

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  • Serialization for memcached

    - by Ram
    I have this huge domain object(say parent) which contains other domain objects. It takes a lot of time to "create" this parent object by querying a DB (OK we are optimizing the DB). So we decided to cache it using memcached (with northscale to be specific) So I have gone through my code and marked all the classes (I think) as [Serializable], but when I add it to the cache, I see a Serialization Exception getting thrown in my VS.net output window. var cache = new NorthScaleClient("MyBucket"); cache.Store(StoreMode.Set, key, value); This is the exception: A first chance exception of type 'System.Runtime.Serialization.SerializationException' occurred in mscorlib.dll SO my guess is, I have not marked all classes as [Serializable]. I am not using any third party libraries and can mark any class as [Serializable], but how do I find out which class is failing when the cache is trying to serialize the object ? Edit1: casperOne comments make me think. I was able to cache these domain object with Microsoft Cache Application Block without marking them [Serializable], but not with NorthScale memcached. It makes me think that there might be something to do with their implementation, but just out of curiosity, am still interested in finding where it fails when trying to add the object to memcached

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  • What's the best way to cache a growing database table for html generation?

    - by McLeopold
    I've got a database table which will grow in size by about 5000 rows a hour. For a key that I would be querying by, the query will grow in size by about 1 row every hour. I would like a web page to show the latest rows for a key, 50 at a time (this is configurable). I would like to try and implement memcache to keep database activity low for reads. If I run a query and create a cache result for each page of 50 results, that would work until a new entry is added. At that time, the page of latest results gets new result and the oldest results drops off. This cascades down the list of cached pages causing me to update every cache result. It seems like a poor design. I could build the cache pages backwards, then for each page requested I should get the latest 2 pages and truncate to the proper length of 50. I'm not sure if this is good or bad? Ideally, the mechanism I use to insert a new row would also know how to invalidate the proper cache results. Has someone already solved this problem in a widely acceptable way? What's the best method of doing this? EDIT: If my understanding of the MYSQL query cache is correct, it has table level granularity in invalidation. Given the fact that I have about 5000 updates before a query on a key should need to be invalidated, it seems that the database query cache would not be used. MS SQL caches execution plans and frequently accessed data pages, so it may do better in this scenario. My query is not against a single table with TOP N. One version has joins to several tables and another has sub-selects. Also, since I want to cache the html generated table, I'm wondering if a cache at the web server level would be appropriate? Is there really no benefit to any type of caching? Is the best advice really to just allow a website site query to go through all the layers and hit the database every request?

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  • How can I test caching and cache busting?

    - by Nathan Long
    In PHP, I'm trying to steal a page from the Rails playbook (see 'Using Asset Timestamps' here): By default, Rails appends assets' timestamps to all asset paths. This allows you to set a cache-expiration date for the asset far into the future, but still be able to instantly invalidate it by simply updating the file (and hence updating the timestamp, which then updates the URL as the timestamp is part of that, which in turn busts the cache). It‘s the responsibility of the web server you use to set the far-future expiration date on cache assets that you need to take advantage of this feature. Here‘s an example for Apache: # Asset Expiration ExpiresActive On <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$"> ExpiresDefault "access plus 1 year" </FilesMatch> If you look at a the source for a Rails page, you'll see what they mean: the path to a stylesheet might be "/stylesheets/scaffold.css?1268228124", where the numbers at the end are the timestamp when the file was last updated. So it should work like this: The browser says 'give me this page' The server says 'here, and by the way, this stylesheet called scaffold.css?1268228124 can be cached for a year - it's not gonna change.' On reloads, the browser says 'I'm not asking for that css file, because my local copy is still good.' A month later, you edit and save the file, which changes the timestamp, which means that the file is no longer called scaffold.css?1268228124 because the numbers change. When the browser sees that, it says 'I've never seen that file! Give me a copy, please.' The cache is 'busted.' I think that's brilliant. So I wrote a function that spits out stylesheet and javascript tags with timestamps appended to the file names, and I configured Apache with the statement above. Now: how do I tell if the caching and cache busting are working? I'm checking my pages with two plugins for Firebug: Yslow and Google Page Speed. Both seem to say that my files are caching: "Add expires headers" in Yslow and "leverage browser caching" in Page Speed are both checked. But when I look at the Page Speed Activity, I see a lot of requests and waiting and no 'cache hits'. If I change my stylesheet and reload, I do see the change immediately. But I don't know if that's because the browser never cached in the first place or because the cache is busted. How can I tell?

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  • How to setup Thinkpad features on Thinkpad T500

    - by gijoemike
    I have a IBM-Lenovo Thinkpad T500. I was previously a exclusive windows user, but recently installed ubuntu and loving it because of speed and interface. The only thing is that I don't get some features that I came to enjoy in windows. I need help setting these up: Hard-drive protection - active protection software that pauses drive when there is movement My printer doesn't work (can't find the driver for this one): canon Ip2600 A way to change which graphics chip to use while in OS. I have both the integrated and non integrated (dual-graphics). (If not easy to setup, I know there's a way to do it before it boots, but don't know how). CPU performance level - in windows you can pick "high performance", "power saver", etc.. to save batteries. My integrated camera w/light - it works but need an app where I can record videos, take snapshots, etc. can't find one that works. Thanks!

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