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Solving slow CF startup: my elaborating on an Adobe blog entry on a possible solution

Note: This blog post is from 2015. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
The fine folks at the Adobe CF blog posted a blog entry today, on "Sometimes ColdFusion services refuse to start normally post server restart" (by Rahul Upadhyay), which offers some helpful information on one possible solution to the stated problem of slow CF startup.

That said, there are some concerns I have, with respect to how I fear some may read and take action based on it (especially the notion of deleting the cfclasses files, as a possible solution to the problem).

I'm not contradicting Rahul here, just elaborating on some points, as someone who (like some on the CF team) helps people with CF server troubleshooting every day.

I started to write these thoughts as a comment there, and (as often happens) it grew long so I thought it better to be a blog entry rather than a long comment, and point people here. Once I did that I decided to go further still, hoping to really help those interested to consider the issue more carefully. (It also gives me a chance to highlight again the Adobe CF team blog, something I recommend EVERYONE reading this should follow!)

One quick point (and update) for the TL;DR crowd: My recommendation is that you move the cfclasses folder out of that location, as a temporary test, to see if it makes CF startup happen faster. If it does, I explain why and what the implications are in the choices of renaming, deleting, moving, or disabling the related "save class files" feature. Also, I add an update in E.1 below (since posting this) which you may really want to read: consider turning off your anti-virus software's real-time protection against the cfclasses folder to see if that alone helps with startup.

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What's the situation with ColdFusion and Java 7, Java 6 updates, Windows 8, and OS X Mountain Lion?

Note: This blog post is from 2012. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
I see the above questions all the time on lists, forums, twitter, etc., and while I point out the following when I see them, I wanted to share them here as well, in case others have missed them or might find them by searching.

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Could CF image processing be killing your ColdFusion server? Explanation and solutions.

Note: This blog post is from 2012. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Are you having slow ColdFusion pages and wondering what may be the cause? There can of course be many root causes, but a common one that I'm finding lately as I help people is due to using certain of CF's image processing features, especially resizing such as to create thumbnails after a file is uploaded (or when many files are uploaded).

Such folks may be using the CFIMAGE action="resize" tag, or the imageResize() or ImageScaleToFit() functions to do resizing. (Or they may be also processing images using ImageRotate, ImageShear, or ImageTranslate, though the defaults for those are not problematic like the resize/scale tag/function processing).

The "problem" (if this is the cause of a slow page) is due to a default "interpolation" setting for CFIMAGE resizing, imageResize, and ImageScaletoFit. The default may not perform well at all. The good news is that the value is configurable, and you can test to compare quality/performance of difference values, as will explained below. There are still some other things to consider also. (If you're currently using CFIMAGE to do resizing, jump to the last section of this entry to see an example of code switching from the "slow" approach to the faster one. But really, you ought to read the rest of this entry to understand what's being proposed.)

While I offer all the info here for your consideration, if you need help implementing the solution, or better understanding how to find and resolve these or other problems affecting your CF server performance, see more on my CF server troubleshooting consulting services.

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I'll be presenting at RIAcon next weekend: "CF911 ColdFusion Performance Report 2011"

Note: This blog post is from 2011. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
I'm delighted to announce that I'll be presenting at next week's RIAcon conference in the DC area, August 6-7 2011.

My session will be "CF911 ColdFusion Performance Report 2011", a new talk/concept I've created. Here's the description:

Starting a new tradition, veteran CF troubleshooter Charlie Arehart will present a review of the performance aspects of making various choices when working with ColdFusion, especially in recent version(s) of ColdFusion. Leveraging the important value of real load testing (as opposed to the less accurate conclusions from "large loop" testing), Charlie's annual report will help attendees appreciate the performance-related improvements of new/changed features, as well some older features where choices can make an important impact. Depending on the timing of the release of "CF next", the session may cover its new features, but it will certainly cover some things new in CF 9 and 9.0.1.

As I note there, I hope this may become an annual event which I might present at this and/or other conferences. (It's an idea rooted in a similar presentation made by a former colleague, from my first IT career from 1982-1997, where he presented the annual "Jim Damon model 204 Performance Report".)

About RIACon

As for RIAcon, I hope you're considering it. Phil Nacelli and the folks at AboutWeb have been working hard to put together the conference, which in some minds is kind of picking up where CFUnited left off. It will be a more intimate event, much like CFunited was when it first started.

Indeed, some will recognize that the location for RIAcon is across the street from one of the hotels where CFunited was held in its early years, right next to the Twinbrook Metro station in Rockville, MD.

A Personal Connection to the Hotel Location

Even more of a delight for me personally is that the hotel (The Legacy Hotel) is right on the land that was once the location of Congressional Roller Skating Rink (until the late 70's), where my sister and I (and many friends) spent our teen years pretty much whenever we weren't in school. Yep, I was a skating nerd: dance, figures, freestyle, and more. Here's incriminating evidence!

Did you know there's a "request execution limit" on IIS? It's 3, 10, 25, or unlimited, depending...

Note: This blog post is from 2011. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Did you know there's a "request execution limit" on IIS? It's 3, 10, or unlimited, depending on the version of Windows (Vista, 7, 2008) and edition (such as Starter/Home/Basic/Pro/Server).

I'll detail the limits per version/edition below.

I'll also offer a (possibly surprising) workaround that can allow you to get even more requests through IIS, even for a single web site.

(Before I elaborate on that, note that there is a separate issue if you're finding that CF doesn't let you see more than 25 requests at once. That's instead due to a setting in CF/JRun, the maxworkerthreads setting. For more on that, see this blog entry.)

That said, this is a problem which could affect anyone regardless of the app server they may be running behind IIS. (And yes, I do realize that for some, the answer to this problem will be, "see, that's another reason to run Apache." We get that. Let's just focus on this problem for those who choose/have to remain on IIS.)

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New for CF9 (and 9.0.1): a query timeout that may really work, with a caveat

Note: This blog post is from 2010. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
This is a very interesting change in CF9 (and 9.0.1), which has slipped under the radar for the most part it seems.

Did you know there is now a setting in the DSN page of the CF Admin (for most of the Adobe-provided DB drivers) which allows you to set a maximum timeout for queries against that DSN?

It's a new feature enabled for the DataDirect drivers, as updated in CF 9. (You will not see it if you use an "other" datasource type, such as when using a downloaded JDBC driver that you implement on CF.)

The caveat? This timeout is ONLY settable there in the DSN definition, not in CFQUERY (or CFSTOREDPROC) itself, which is a shame. The existing TIMEOUT attribute for those (CF10 added it for CFSTOREDPROC) is not the same and generally does not work. Still, the value of this even at the DSN level is too important to ignore for some challenges. More on that (and some other thoughts) in a moment.

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Some code to throttle rapid requests to your CF server from one IP address

Note: This blog post is from 2010. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Some time ago I implemented some code on my own site to throttle when any single IP address (bot, spider, hacker, user) made too many requests at once. I've mentioned it occasionally and people have often asked me to share it, which I've happily done by email. Today with another request I decided to post it and of course seek any feedback.

It's a first cut. While there are couple of concerns that will come to mind for some readers, and I try to address those at the end, it does work for me and has helped improve my server's stability and reliability, and it's been used by many others.

Update in 2020: I have changed the 503 status code below to 429, as that has become the norm for such throttles. I had acknowledged it as an option originally. I just want to change it now, in case someone just grabs the code and doesn't read it all or the comments. Speaking of comments, do see the discussion below with thoughts from others, especially from James Moberg who created his own variant addressing some concerns, as offered on github, and the conversation that followed about that, including yet another later variant.

Update in 2021: Rather than use my code, perhaps you would rather have this throttling done by your web server or another proxy. It is now a feature offered in IIS, Apache, and others. I discuss those in a new section below.

Background: do you need to care about throttling? Perhaps more than you realize

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New DataDirect JDBC Type 5 drivers (for SQL Server, MySQL, Oracle, and more)

Note: This blog post is from 2010. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
I think most folks know that the underlying database drivers in CF are from DataDirect. Well, they've announced new "Type 5" drivers. While you would have to buy and install them separately from those built-into CF (for now, as Adobe has not yet certified CF for use with them), I think some people may want to give them serious consideration even before then.

Several Performance Advantages, and Failover As Well

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Tracking number of CF sessions per application easily, and why you should care

Note: This blog post is from 2009. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Ever wanted to count how many sessions are active on your server, in total and per application, whether on CF 7 or 8? And regardless of whether you're using CF's regular sessions or the "new" J2EE sessions feature introduced in CF 6? Would you be surprised to find you could have a shocking number of active sessions?

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Several SQL Server Performance Tuning how to's

Note: This blog post is from 2008. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Need to solve problems with SQL Server performance? Here are several resources that can help:

Some of these offer knowledge and understanding, others offer specific steps to follow. Most offer links to still other resources (including often specific entries in Books Online).

Note that some may be written more to those still running SQL Server 7 (less likely) or SQL Server 2000 (not so unlikely), though many do cover SQL Server 2005 as well. Just keep this in mind while reading, both if some step doesn't seem to follow, and also in case it may be that some setting that suits one release may not suit another. In fact, some of the resources specifically discuss how things have changed in later releases, and how in fact some settings or techniques for older releases may be very different for later ones. All this just calls for discernment while you read.

These are all in addition to a couple of entries I wrote back in April (starting here) on some other advanced tools and techniques for diagnosing SQL Server problems.

Sometimes CF gets blamed for problems when in fact the problem is in the DBMS--and it's not always a problem due to the SQL being sent from CF. Sometimes the same code can run very differently one time than another. In that case, you really need to understand why this is happening. I hope the resources above may help you. If you ever want direct assistance, this is one of the things I help people with in my available consulting.

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