Category Archives: Perfromance

Reduce Technical Debt Part 2 – Empty Try Catch

Here is a the second in the series on how to reduce Technical Debt, please read part one as it gives an insight into the scale and challenges we faced, and outlines what this blog post is trying to address.

As you are aware the first part introduced a few code examples to help remove redundant code, this blog will continue to focus on how to remove redundant code by introducing the EmptyTryCatchService class and the IgnoreEmptyTryCatch Custom attribute .

But before that I just briefly want to mention integrations, in my experience this is where a lot of redundant and or unnecessary code can hide.

Integrations

Therefore, an important concept to reduce technical debt, is to identify, separate and isolate dependencies on external systems, especially complex and or legacy systems.

I have already written a blog series about this, so if you missed please read it.

Integrations Platform

I believe in an ideal world, most integrations and especially complex and or legacy system specific code should be move out of the website solution to an integration platform!

Most issues, difficulties, problems and cost relating to code maintenance and technical debt for website is due to being responsible for stuff they should not be.

For example, the website is responsible for aggregation data from several systems to provide a unified view of their data, NO this is the job of an Integrations/aggregation platform

Empty Try Catch

So, let me start by stating – ignoring exceptions is a bad idea, because you are silently swallowing an error condition and then continuing execution.

Occasionally this may be the right thing to do, but often it’s a sign that a developer saw an exception, didn’t know what to do about it, and so used an empty catch to silence the problem.

It’s the programming equivalent of putting black tape over an engine warning light.

It’s best to handle exceptions as close as possible to the source, because the closer you are, the more context you have to achieve doing something useful with the exception.

Ignore Empty Try Catch – Custom attribute

In some rare cases the empty try catch can be valid, in which case you can use the custom attribute to mark the function and explain why it is OK, and check one last time is there not a TryParse version of the function and or code you are calling.

Performance

Slightly off topic, but still a type of technical debt, do not use exceptions for program flow!

Throwing exceptions is very expensive (must dump the registries, call stack, etc. and whilst doing this it blocks all threads) so it has a big impact on performance.

I have seen sites brought to their knees because of the number exceptions being thrown.

Redundant Code

In the solution we took over there were over 300 empty try-catch statements ☹

But how can it hide redundant code?

When an exception is thrown it can jump over lots of code, which is therefore never called.

Therefore, all the code after the exception is redundant.

Below is the classic Hello World program it works as expected, it prints out “Hello World”.

But there is a lot of technical debt, now this might look like a funny example, but I have seen a lot of similar examples in real world, usually with a lot more code in the try catch, and usually found most often around big complex integrations!

try catch redunant code

Solution – EmptyTryCatchService

For empty try catches I would not recommend you use Sitecore’s standard logging, as it can create enormous log files which is enough to kill your sitecore solution, if the empty try catch is called a lot.

For tracking down empty try catches, it is good to have a dedicated log file and a way to limit the amount of data written to the log file.

EmptyTryCatchService class provides the following features:

  • Report interval – the interval between exceptions with the same owner, name and exception message are written to the log file.
  • Max Log limit – when the number exceptions with the same owner, name and exception message is exceed no more data is written to the log file.
  • Dedicated log file for each day
  • Disable all logging via configuration.

EmptyTryCatchService class is a simple class that, relies on the MaxUsageLog for most of its functionality (see the code below).

In addition to finding redundant code the EmptyTryCatchService will track down hidden errors and problems in your solution, which will result in a reduction of the technical debt.

You must be careful when reviewing the exceptions logged and deciding how best to deal with the exceptions. See part 3 in the series, to reduce technical debt.

public class EnsureIsObsoleteService
{
private readonly MaxUsageLog _maxUsageLog =
new MaxUsageLog(10000, "EnsureIsObsoleteService",1000);
public void EnsureIsObsolete(object owner, string message)
{
_maxUsageLog.Log(owner, message);
}
}
public class MaxUsageLog
{

public MaxUsageLog(int maxLogLimit,
string fileNamePrefix,
int reportCountInterval=1000000)
{
_maxLogLimit = maxLogLimit;
_fileNamePrefix = !string.IsNullOrEmpty(fileNamePrefix) ? fileNamePrefix : "MaxUsageLog";
_reportCountInterval = reportCountInterval;
}

public void Log(object owner, string message, Exception ex = null)
{
if (!IsEnabled())
return;

string type = string.Empty;
if (owner != null)
{
if (owner is Type typeObj)
{
type = typeObj.FullName;
}
else
{
type = owner.GetType().FullName;
}
}
string key = GenerateKey(type, message, ex);
if (!ShouldLog(owner, key))
return;
var count = Count(key);
WriteToFile(owner, type, message, ex, count);
}

private int Count(string key)
{
return Usage.ContainsKey(key) ? Usage[key] : 0;
}

private void WriteToFile(object owner, string type, string message, Exception exceptionToLog, int count)
{
try
{
StreamWriter log = File.Exists(FileName) ? File.AppendText(FileName) : File.CreateText(FileName);
try
{
log.AutoFlush = true;
log.WriteLine($"{DateTime.Now.ToUniversalTime()}: Type:'{type}' Message:'{message}' Count:{count}");
if (exceptionToLog != null)
{
log.WriteLine($"Exception:{exceptionToLog}");
}
log.Close();
}
finally
{
log.Close();
}
}
catch (Exception ex)
{
if (!Sitecore.Configuration.ConfigReader.ConfigutationIsSet)
return;
Sitecore.Diagnostics.Log.Error(
$"Failed writing log file {FileName}. The following text may be missing from the file: Type:{type} Message:{message}",
ex, owner);
}
}
private bool ShouldLog(object owner, string key)
{
if (!Usage.ContainsKey(key))
{
Usage.Add(key, 1);
return true;
}
var count = Usage[key] = Usage[key] + 1;

if (count % _reportCountInterval == 0)
{
WriteToFile(owner, "******** Report Count Interval ******", $"Key:'{key}'", null,count);
}

if (count > _maxLogLimit)
return false;
if (count == _maxLogLimit)
{
WriteToFile(owner, "******** Usage Max Exceeded ******", $"Key:'{key}' Max Limit:{_maxLogLimit}",null,count);
return false;
}
return true;
}
private string GenerateKey(string type, string message, Exception ex)
{
return ex != null ?
$"{_fileNamePrefix}_{type}_{message}_{ex.HResult}" :
$"{_fileNamePrefix}_{type}_{message}";
}

private string FileName
{
get
{
DateTime date = DateTime.Now;
string fileName = $@"\{_fileNamePrefix}.{date.Year}.{date.Month}.{date.Day}.log";

if (!Sitecore.Configuration.ConfigReader.ConfigutationIsSet)
return ConfigurationManager.AppSettings[Constants.Configuration.Key.LogFolderForApplications] + fileName;

return Sitecore.MainUtil.MapPath(Sitecore.Configuration.Settings.LogFolder) + fileName;
}
}

private bool IsEnabled()
{
if (!Sitecore.Configuration.ConfigReader.ConfigutationIsSet)
return StringToBool(ConfigurationManager.AppSettings[Constants.Configuration.Key.MaxUsageLogEnabled],false);

return Sitecore.Configuration.Settings.GetBoolSetting(Constants.Configuration.Key.MaxUsageLogEnabled, true);
}

private bool StringToBool(string value, bool defaultValue)
{
if (value == null)
return defaultValue;
bool result;
if (!bool.TryParse(value, out result))
return defaultValue;
return result;
}

private readonly int _maxLogLimit;
private readonly string _fileNamePrefix;
private readonly int _reportCountInterval;

// this is to ensure we can count how many times a message has been logged across all threads
private static readonly Dictionary<string, int> Usage = new Dictionary<string, int>();
}

Hope this was of help, Alan

 

Reduce Technical Debt and Redundant Code

A while ago, we at Pentia took over a massive Sitecore solution, which after 15 years of upgrades and development the maintenance cost consumed the entire digital budget of the customer.

In other words, the client was at a crossroad – to build new or renovate.

For this client the answer was relatively easy:

  • Firstly, the number of features and functionalities in the platform is vast, and just to scope and specify the entire platform was a massive, if not impossible, undertaking – and one which would claim a large number of resources internally and externally.
  • Secondly, while building a new platform (a massive task), the existing platform would have to be kept alive and slowly (painfully slowly) phased out over time. This means double resources for development, maintenance and operations.
  • Thirdly – and probably the most deterring factor – the change management involved in retraining the thousands of staff involved in and around the platform and across departments was substantial and disruptive to the entire organisation.

Therefore, a renovation project was established, and the first task was to reduce technical debt for the solution.

Reducing maintenance cost

One of the best ways to reduce technical debt is to reduce the code base, less code == less maintenance cost. In this case we managed to delete 28% of the code base, here are a few key figures for the solution when we took it over.

  • 900+ sites (over ½ million items)
  • 15 years old (multiple upgrades from Sitecore 4.x to 8.2 and single migration)
  • 15 integrations
  • 600+ Layouts/sub layouts
  • Many JavaScript applications (Angular/React/Backbone/knockout/native/JQuery)
  • Code
    • 294030 lines code
    • Cyclomatic Complexity – main project 9662 average 1200
    • Depth of Inheritance – main project 17 average 8
    • Class Coupling – main project 1400, average 500
  • Single solution multiple roles
    • Content management
    • Content delivery
    • Publishing
    • Utility/API
    • Bot
  • No Access to production (apart from Sitecore client)
  • Manual deploys to Production
  • 2 separate solutions (Intranet & Websites) merged into a single solution 4 years ago
  • Not Helix compliant (sort of n-tier where projects had numbers)

The Challenge

Due to the sheer size of the solution, no one in the client’s organisation really knew which features were used and how much. There were many clear indications of code not being used or referred.

So, the initial task was to identify and remove unnecessary parts of the solution.

But how to you identify redundant code?

Visual studio has tools for that, unfortunately Sitecore/web application introduce additional challenges as un-referenced C# code can still be executed due to the following:

  • Configuration – pipelines, event handlers, custom configuration, etc.
  • Sitecore content – items that define that specific functions on a class should be executed i.e. WFFM.
  • Sitecore rendering engine that renders the presentation using web controls, layouts, sub layouts, controllers, code, etc.

In addition, then we must identify if the code used by the following is ever called

  • Layouts
  • Sub Layouts
  • Controllers
  • Web Controls
  • XSLT’s
  • Rest APi’s
  • Soap Web Services

Solution

As in most renovation projects, there is no silver bullet, it requires a longsighted plan, structured methodology, concepts, code, tools and continuous effort to reduce technical debt.

Ironically to reduce the code base you must introduce more code.

Custom Attributes

We introduced several custom attributes to help mark up the code and help identify issues to be address.

  • Obsolete
  • Used
  • Refactor
  • Ignore Empty Try Catch (see part 2)

Used

The point of this attribute is to clearly mark that a loosely referenced class, method or interface is indeed needed by the solution.

In other words, it indicates that a class, method or interface is used, even though it has no references. It’s possible to add a text to explain how and where it is used.

Obsolete

Whilst .net provides the Obsolete custom attribute; there are some missing options to indicate that the code is obsolete, and can be removed when a condition is met:

  • Specific date
  • Specific release is in production
  • 3rd party system is updated to a specific version

The point of this attribute was therefore to allow us to plan the renovation project in stages and remove code when the referring parts were cleaned up.

Refactor

During this project we ran into many pieces of code, classes and structures which were in dire need of refactoring. But because of constraints in time, code not deployed, lack of knowledge, dependencies, multiple version of 3rd party system, or for some other reason it was not possible at that time.

Therefore, the best we could do was add this attribute and define why it should be refactored, and why it hasn’t been refactored.

The purpose of this attribute was therefore documentation and planning of the renovation process

Introducing a “Ensure Code Is Obsolete” Service

It is very difficult to ensure that code is obsolete and is never called and that is why it is so difficult to delete code.

What we needed was a somewhat conclusive measurement if the running code was being executed.

What we decided to do was to introduce code in the solution that collected data on code executed across all running solution instances and aggregated the data and presented the results, to ensure that the code was not required.

The IIncrementCountService interface was introduced to provide the ability to count how often the code is executed and then send the results to be aggregated with the other instances, by the content management server.

public interface IIncrementCountService
{
  bool IncrementCount(Type type,string name);
}

Implementation Challenges

The Content Management, Content Delivery, Utility & API instances are in different network zones without access to each other.

The implementation must have a minimum impact on performance, network traffic, database storage.

Not introduce any new databases and or tables.

As we do not have access to production environment apart from the Sitecore Client, it is not possible log the data the file system.

Sitecore Remote Events

Remote events (see this blog for a good introduction) provide the perfect mechanism to allow all instances to send their counter data to the Content Management service which is responsible for aggregating the data and presenting the results.

You must be careful with events as if you flood the event queue table it can kill the performance of ALL your sitecore instances.

The following configuration was introduced (see my blog post on Type Safe Settings) so the IncrementCount function will only raises an event when one of the following is true:

  • The count exceeds 1000
  • The threshold of 15 minutes is reached
  • A new day starts

This ensures that the event queue is not overloaded and will minimize performance impact, network & database usage.

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:environment="http://www.sitecore.net/xmlconfig/environment" xmlns:role="http://www.sitecore.net/xmlconfig/role/"&gt;
	<sitecore>
		<feature>
			<Diagnostics>
				<CounterSettings type="Feature.Diagnostics.Infrastructure.CounterSettings, Feature.Diagnostics" singleInstance="true">
					<ThresholdCount>1000</ThresholdCount>
					<ThresholdTime>15</ThresholdTime>
					<Enabled>true</Enabled>
				</CounterSettings>
			</Diagnostics>
		</feature>
	</sitecore>
</configuration>

The IncrementLocalCountService class is responsible for incrementing the count, caching it locally and raising the event to notify the Content Management server, when one of the afore mention threshold is met.

   public class IncrementLocalCountService : IIncrementCountService
    {
        private readonly IList&lt;Counter&gt; _counters = new List&lt;Counter&gt;();
        private readonly CounterFactory _counterFactory;
        private readonly CounterUpdateRemoteEventFactory _counterUpdateRemoteEventFactory;
        private readonly CounterSettings _counterSettings;

        public IncrementLocalCountService([NotNull]CounterFactory counterFactory,
            [NotNull]CounterUpdateRemoteEventFactory counterUpdateRemoteEventFactory,
            [NotNull]CounterSettings counterSettings)
        {
            Assert.ArgumentNotNull(counterFactory, nameof(counterFactory));
            Assert.ArgumentNotNull(counterUpdateRemoteEventFactory, nameof(counterUpdateRemoteEventFactory));
            Assert.ArgumentNotNull(counterSettings, nameof(counterSettings));
            _counterFactory = counterFactory;
            _counterUpdateRemoteEventFactory = counterUpdateRemoteEventFactory;
            _counterSettings = counterSettings;
        }

        public bool IncrementCount(Type type,string name)
        {
            if (string.IsNullOrWhiteSpace(name))
                return false;
            if (_counterSettings == null || !_counterSettings.Enabled)
                return false;

            DateTime today = DateTime.Now.Date;
            // any from yesterday Flush
            Counter counter = _counters.FirstOrDefault(c =&gt; c.Name == name &amp;&amp; c.Date == today &amp;&amp; c.Type == type);
            if (counter == null)
            {
                counter = _counterFactory.Create(name, today, 0);
                _counters.Add(counter);
            }
            counter.Count++;
            Flush(today);
            return true;
        }

        private void Flush(DateTime today)
        {
            //iterate over all counters, flush that exceed the threshold count or time restriction
            foreach (var counter in GetThresholdExceeded())
            {
                RaiseEvent(counter);
                _counters.Remove(counter);
            }
        }

        private IEnumerable&lt;Counter&gt; GetThresholdExceeded()
        {
            DateTime timeLimit = DateTime.Now.Subtract(new TimeSpan(0, _counterSettings.ThresholdTime, 0));
            return _counters.Where(c =&gt; c.Created &lt; timeLimit || c.Count &gt;= _counterSettings.ThresholdCount).ToList();
        }

        private void RaiseEvent(Counter counter)
        {
            if (counter == null)
                return;
            var counterUpdateRemoteEvent = _counterUpdateRemoteEventFactory.Create(counter.Name, counter.Date, counter.Count);
            Sitecore.Eventing.EventManager.QueueEvent(counterUpdateRemoteEvent,true,true);
        }
    }

Who is responsible for aggregating the results?

The content Management is responsible for aggregating the results. It requires some extra configuration, to register that it will subscribe to handle remote events, raise the event and it then handle the remote event (see blog for more information).

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:set="http://www.sitecore.net/xmlconfig/set/" xmlns:role="http://www.sitecore.net/xmlconfig/role/"&gt;
	<sitecore role:require="Standalone OR ContentManagement"&gt;
		<events>
			<event name="counter:update:remote">
				<handler type="Feature.Diagnostics.Infrastructure.Events.Counter.CounterUpdateRemoteEventHandler, Feature.Diagnostics" method="Update" />
			</event>
		</events>
		<pipelines>
			<initialize>
				<processor type="Feature.Diagnostics.Infrastructure.Pipelines.Counter.SubscribeToCounterRemoteEventService, Feature.Diagnostics" />
			</initialize>
		</pipelines>
	</sitecore>
</configuration>

The code associated with the configuration above.

    public class CounterUpdateRemoteEventHandler
    {
        public void Update(object sender, EventArgs args)
        {
            if (args == null)
                return;

            try
            {
                var countRemoteEventArgs = args as RemoteEventArgs<CounterUpdateRemoteEvent>;
                Assert.IsNotNull(countRemoteEventArgs, $"Unexpected event args: {args.GetType().FullName}");
                Assert.IsNotNull(countRemoteEventArgs.Event, $"Event is nul: {args.GetType().FullName}");

                var counterRepository = ServiceLocator.ServiceProvider.GetService<CounterRepository>();
                Assert.IsNotNull(counterRepository, $"Could not resolve type:{typeof(CounterRepository).FullName}");

                var counterFactory = ServiceLocator.ServiceProvider.GetService<CounterFactory>();
                Assert.IsNotNull(counterFactory, $"Could not resolve type:{typeof(CounterFactory).FullName}");

                var @event = countRemoteEventArgs.Event;
                var counter = counterFactory.Create(@event.Name, @event.Date, @event.Count);
                if (counter == null)
                    return;
                counterRepository.Update(counter);
            }
            catch (Exception exception)
            {
                Log.Error($"CounterUpdateRemoteEventHandler.Update - failed", exception);
            }
        }
    }

    public class SubscribeToCounterRemoteEventService
    {
        public void Process(PipelineArgs args)
        {
            Sitecore.Diagnostics.Log.Info("SubscribeToCounterRemoteEventService.Initialize Called",this);
            var action = new Action<CounterUpdateRemoteEvent>(RaiseRemoteEvent);
            EventManager.Subscribe(action);
        }

        public void RaiseRemoteEvent(CounterUpdateRemoteEvent counterUpdateRemoteEvent)
        {
            if (counterUpdateRemoteEvent == null)
                return;
            RemoteEventArgs<CounterUpdateRemoteEvent> remoteEventArgs = new RemoteEventArgs<CounterUpdateRemoteEvent>(counterUpdateRemoteEvent);
            Event.RaiseEvent(counterUpdateRemoteEvent.EventName, remoteEventArgs);
        }
    }

Where is the Data Saved?

Ideally it should be saved in its own SQL database.

Unfortunately, we were not allowed to introduce and new databases and or tables, so we had to use the sitecore IDTable. The CounterRepository is responsible for retrieving, updating and  persisting the counters in the IDTable.

    public class CounterRepository
    {
        private readonly CounterFactory _counterFactory;
        private readonly GenerateKeyService _generateKeyService;

        public CounterRepository([NotNull] CounterFactory counterFactory, 
            [NotNull]GenerateKeyService generateKeyService)
        {
            Assert.ArgumentNotNull(counterFactory, nameof(counterFactory));
            Assert.ArgumentNotNull(generateKeyService, nameof(generateKeyService));
            _counterFactory = counterFactory;
            _generateKeyService = generateKeyService;
        }

        public bool Update([NotNull] Counter counter)
        {
            Assert.ArgumentNotNull(counter, nameof(counter));

            var counterInDatabase = Get(counter.Name, counter.Date);
            if (counterInDatabase == null)
                return Add(counter);
            counter.Count += counterInDatabase.Count;
            Delete(counterInDatabase);
            return Add(counter);
        }

        public IEnumerable<Counter> Get()
        {
            var idTableEntries = IDTable.GetKeys(Constants.IdTable.Prefix);
            return idTableEntries == null ? new List<Counter>() : _counterFactory.Create(idTableEntries);
        }

        private bool Add(Counter counter)
        {
            if (counter == null)
                return false;
            var idTableEntry = IDTable.Add(Constants.IdTable.Prefix,
                _generateKeyService.GenerateKey(counter.Name, counter.Date),new ID(Guid.NewGuid()),
                ID.Null,counter.Count.ToString());
            return idTableEntry != null;
        }

        private void Delete(Counter counter)
        {
            if (counter == null)
                return;

            IDTable.RemoveKey(Constants.IdTable.Prefix, _generateKeyService.GenerateKey(counter.Name, counter.Date));
        }

        private Counter Get(string name, DateTime date)
        {
            if (string.IsNullOrWhiteSpace(name))
                return null;

            var idTableEntry = IDTable.GetID(Constants.IdTable.Prefix, _generateKeyService.GenerateKey(name, date));
            if (idTableEntry == null)
                return null;
            if (!long.TryParse(idTableEntry.CustomData, out var count))
                count = 0;
            return _counterFactory.Create(name, date, count);
        }

      }

Presenting the results

No magic here a simple counter.aspx pages, which reads from the CounterRepository and displays it in a table, with the option to clear the database. Also some code to ensure that only Sitecore administrators can access the page. See Part 2 in the series.

How to kill Sitecore whilst getting the languages for an item

I was reviewing a solution (not developed by Pentia) for a customer as they were concerned about the performance and stability of their site.

It didn’t take me long to find the following bit of code which calls the SQL server to find the languages for a given item:

languages

I was shocked that anyone would not use the Languages property on the Item class, which would have replaced the entire function.

I think in all my years of Sitecore development this is the worst bit of code I have ever seen, it shows  a complete lack of respect for the API and if  the site was upgraded it is possible that the database schema could change and therefore the code would break!

On average the SQL query took 400mS (which is quite slow, but then again the SQL server was getting hit by 4 front end servers for every request).

The same call to the Item.languages took 0.1mS, this simple change made every request 400mS quicker and reduced the load on the SQL server considerably.