I am trying to use Hudson filesystem SCM to monitor an area, and kick of a build when it changes. It has been working fine with one area. I have just added a new job for nother area, and told it to "clear workspace". This seems to go into a spin - I've had builds queued up continuously, each claiming to have found 2396 new files. The documentation for the plugin suggests this sould be working, and I can't imaging why they would have provided the feature if this is not how I am supposed to use it, but any ideas what is wrong?
I think I have fixed it. It was polling every minute, but taking several minutes to fetch. I had expected that polling would be suspended while the build was under way, but it is not, so the next one along found lots of missing files in the frechly cleared folder. Setting the polling interval to
0,10,20,30,40,50 * * * *
seems to have fixed it.
Related
I followed this tutorial to implement push notifications in my web app, and while they work, they stop working very quickly. It seems to handle the first couple of notifications well, but after that, sometimes when less than five minutes has gone by, the subscription expires, according to my back-end. I get an error code of 410 from the push service which the tutorial says is meant to indicate that the subscription expired.
This is crazy, how can a subscription expire in less than five minutes? I searched up my issue and it seems no one else has had this problem, some even saying that subscriptions can last years!
I tried implementing an event listener in my service worker for the "pushsubscriptionchange" event, but according to Serginho's answer, Chrome did not implement that event as of 2019, and I don't think that's changed since then.
Oh, and while Chrome can handle the subscription (but only once/twice as explained above), Firefox doesn't even do anything. I feel like I'm going crazy. If I test the push subscription feature itself using this site, however, it works in Firefox! and Chrome! What are they doing that I'm not? They show the exact same code as the tutorial I linked above.
What even can I do at this point? I've considered perhaps creating an interval with setInterval() and just resubscribing the user every second or so, but I don't think that'll work.
Any help would be appreciated.
You absolutely need to handle the pushsubscriptionchange in your service worker. Otherwise when a subscription expires and is replaced with a new one you will lose it.
Chrome and most browsers actually trigger that event (I don't know where you read something different). I am sure that it is triggered because on our push service we receive thousands of hits per hour from that event.
Take a look at our service worker if you need inspiration on how to implement that event. Then on your server you simply replace the old subscription with the new one.
I want to monitor a chatroom with a selfwritten chrome extension. Because I don't know anything about the scripts behind the chatroom system itself, I thought about a simple timer and export script.
My idea is a periodical timer (let's say every second, because it has to react as fast as possible) calling a function, which reads the complete HTML of the current tab (with chrome.pageCapture.saveAsMHTML) and sends the hole HTML to an external REST service (via XMLHttpRequest()).
I know that this approach is very ressource consuming, but that doesn't matter as all this will run on a dedicated computer. Of course I thought about using chrome.webRequest.onCompleted to trigger the export but, as already mentioned, i have no idea about the technical interna of the chatroom.
Unfortunately I can't find any API to create a time base on seconds, but only on minutes (chrome.alarms.create). Or is there a more elegant way to do this job?
Any hints appreciated.
More elegant way would be to use a MutationObserver, at least as a source of a "there are some changes" event. But maybe the chat is implemented in such way that getting the changes (and then sending only changes, not the whole page) will be convenient too.
I have a "standard persistent disk" of size 10GB on Google Cloud using Ubutu 12.04. Whenever, I try to remove this, I encounter following error
The resource 'projects/XXX/zones/us-central1-f/disks/tahir-run-master-340fbaced6a5-d2' is not ready
Does anybody know about what's going on? How can I get rid of this disk?
This happened to me recently as well. I deleted an instance but the disk didn't get deleted (despite the auto-delete option being active). Any attempt to manually delete the disk resource via the dev console resulted in the mentioned error.
Additionally, the progress of the associated "Delete disk 'disk-name'" operation was stuck on 0%. (You can review the list of operations for your project by selecting compute -> compute engine -> operations from the navigation console).
I figured the disk-resource was "not ready" because it was locked by the stuck-operation, so I tried deleting the operation itself via the Google Compute Engine API (the dev console doesn't currently let you invoke the delete method on operation-resources). It goes without saying, trying to delete the operation proved to be impossible as well.
At the end of the day, I just waited for the problem to fix-itself. The following morning, I tried deleting the disk again, as it looks like the lock had been lifted in the meantime, as the operation was successful.
As for the cause of the problem, I'm still left clueless. It looks like the delete-operation was stuck for whatever reason (probably related to some issue or race-condition going on with the data-center's hardware/software infrastructure).
I think this probably isn't considered as a valid answer by SO's standards, but I felt like sharing my experience anyway, as I had a really hard time finding any info about this kind of google cloud engine problems.
If you happen to ever hit the same or similar issue, you can try waiting it out, as any stuck operation will (most likely) eventually be canceled after it has been in PENDING state for too long, releasing any locked resources in the process.
Alternatively, if you need to solve the issue ASAP (which is often the case if the issue is affecting any resource which is crtical to your production environment), you can try:
Contacting Google Support directly (only available to paid support customers)
Posting in the Google Compute Engine discussion group
Send an email to gc-team(at)google.com to report a Production issue
I believe your issue is the same as the one that was solved few days ago.
If your issue didn't happen after performing those steps, you can follow Andrea's suggestion or create a new issue.
Regards,
Adrián.
A Django site (hosted on Webfaction) that serves around 950k pageviews a month is experiencing crashes that I haven't been able to figure out how to debug. At unpredictable intervals (averaging about once per day, but not at the same time each day), all requests to the site start to hang/timeout, making the site totally inaccessible until we restart Apache. These requests appear in the frontend access logs as 499s, but do not appear in our application's logs at all.
In poring over the server logs (including those generated by django-timelog) I can't seem to find any pattern in which pages are hit right before the site goes down. For the most recent crash, all the pages that are hit right before the site went down seem to be standard render-to-response operations using templates that seem pretty straightforward and work well the rest of the time. The requests right before the crash do not seem to take longer according to timelog, and I haven't been able to replicate the crashes intentionally via load testing.
Webfaction says that isn't a case of overrunning our allowed memory usage or else they would notify us. One thing to note is that the database is not being restarted (just the app/Apache) when we bring the site back up.
How would you go about investigating this type of recurring issue? It seems like there must be a line of code somewhere that's hanging - do you have any suggestions about a process for finding it?
I once had some issues like this, and it basically boiled down to my misunderstanding of thread-safety within django middleware. Basically the django middleware is I believe a singleton that is shared among all threads, and these threads were thrashing with the values set on a custom middleware class I had. My solution was to rewrite my middleware to not use instance or class attributes that changed, and to switch the critical parts of my application to not use threads at all with my uwsgi server as these seemed to be an overall performance downside for my app. Threaded uwsgi setups seem to work best when you have views that may complete at different intervals (some long running views and some fast ones).
Since you can't really describe what the failure conditions are until you can replicate the crash, you may need to force the situation with ab (apache benchmark). If you don't want to do this with your production site you might replicate the site in a subdomain. Warning: ab can beat the ever loving crap out of a server, so RTM. You might also want to give the WF admins a heads up about what you are going to do.
Update for comment:
I was suggesting using the exact same machine so that the subdomain name was the only difference. Given that you used a different machine there are a large number of subtle (and not so subtle) environmental things that could tweak you away from getting the error to manifest. If the new machine is OK, and if you are willing to walk away from the problem without actually solving it, you might simply make it your production machine and be happy. Personally I tend to obsess about stuff like this, but then again I'm also retired and have plenty of time to play with my toes. :-)
I just got a mail saying that I have to change a config value at 2009-09-01 (new taxes). Our normal approach for this would be to to awake at 2009-08-31 at 23:59 and then just change the value manually. Which not is a big problem since this don't happens to often. But it makes me wonder how other people handle issues like this.
So! How do you handle date specific config changes?
(We are working in asp.net but I don't think this has to be language specific)
Br
Carl Bergquist
I'd normally store this kind of data in a database table like this
Key, Value, EffectiveFrom, EffectiveTo
-----------------------------------------
VAT, 15.0, 20081201, 20091231
VAT, 17.5, 20100101, NULL
I'd then use the EffectiveFrom and EffectiveTo dates to chose the value that is effective at the given time. If the rate is open ended then the effecive to could either by NULL or 99991231.
This also allows you to go back without having to change the config. E.g. if someone asks you to recalculate the tax for the previous month before the rate change.
In linux, there is a command "at" for batch execution.
See "man at" for details.
To be honest, waking up near the time and changing it seems to be the simplest and cheapest approach. All of the technical solutions are fine, but it depends where you work.
In our environment it would be cheaper and simpler to get someone to wake up and make the change than to redevelop the functionality of a piece of software that already works. It certainly involves less testing, development overhead and costs which means we would tend to solve the problem as you do, manually.
That depends totally on the situation and the technology.
pjp's idea is good, if you get your config from a database, or as metadata to define the valid time for whole config sets/files.
Another might be: just prepare a new configfile with the new entries and swap them at midnight (probably with a restart of the service/program) whatever.
Swapping them would be possible with at (as given bei Neeraj) ...
If timing is a problem you should handle the change, or at least the timing of the change on the running server (to avoid time out of synch problems).
We got same kind of problem some time before and handled using the following approach.
this is suitable if you are well known to the source that orginates the configuration changes..
In our case, the source exposed a webservice (actualy a third party) which will return a modified config details. And there is a windows service running on our server which keeps on polling the webservice and will update the configuration file if there is any change.
this works perfectly in our case..
You can make use of this approach by changing the polling webservice part to your source of config change (say reading changes from some disk path). But am not sure how this is possible reading config changes from email.
Why not just make a shell script to swap out the files. run it in cron and switch the files out a minute before and send an alert text if NOT successful and an email if successful.
This is an example on a Linux box but I think you get the point and can do this on a Windows box.
Script:
cp /path/to/old/config /path/to/backup/dir/config.timestamp
cp /path/to/new/config
if(/path/to/new/config exsits) {
sendSuccessEmail();
} else {
sendPanicTextAlert();
}
cron:
59 23 31 8 * /path/to/script.sh
you could test this as well before hand just point to some dummy directories and file
I've seen the hybrid approach. Instead of actually changing the data model to include EffectiveDate/EndDate or manually changing the values yourself, schedule a script to change the values automatically. Also, be sure to have a solid test plan that will validate all changes.
However, this type of manual change can have a dramatic impact on reporting. If previous transactions join directly to the tables being changed, numbers in historical reports could change in a very bad way. There really is no "right" answer.
If I'm not able to do something like pjp's solution, I'd use either a scheduled task or a server job to update it automatically at the right time.
But...I'd probably still be awake checking it had worked.
Look the best solution would be to parameterise your config file and add things like when a certain entry should be used from. This would negate the need for any copying or swapping of files and your application would simply deal with it. (That goes for a config file approach or a database)
If you cannot change the current systems and you have to go with swapping the config files, then you also have two options:
Use a scheduled task to kick off a batch job or even a VBScript or PowerShell script (which ever you feel comfortable with) Make sure you set up the correct credentials to be able to do this at the middle of the night and you could also add some checking and mitigation into this approach.
Write a windows Service that does this for you. Here you have all the flexibility you need. Code it to do whatever it needs to do, do all the checks you need to (so that you can keep sleeping rather than making sure it actually worked) etc, etc. You service would then even take care of the scheduling aspect and all will be good. Here you could use xml DOM object and xPath and not replace the file, but simply update the specific entries as required.
Remember that any change to the config file would cause your site to restart, so make sure you take care of all the other housekeeping stuff that this could cause. (Although this would be exactly the same if you where sitting there in the middle of the night copying file around)