Best Practices to Resolve Resource Contention in the Cloud
October 18, 2012
Assaf Sagi
Share this

Preventing a slow application caused by probable resource contention requires a rigorous methodological approach and an appropriate toolset. IT managers, working with business owners, should prioritize critical apps for multi-tenancy and maximum performance.

Resource contention is what happens when demand exceeds supply for a shared resource, such as memory, CPU, network or storage. In modern IT, where cost cuts are the norm, addressing resource contention is a top priority. The main concern with resource contention is the performance degradation that occurs as a result.

When two or more transactions are racing for the same resource, one of them will get it and the others will have to wait in line until the resource is available, meanwhile causing user frustration. This problem is not new, considering the common scenario of two processes on the same machine competing for the same physical CPU or memory. Another typical scenario involves two database transactions fighting for I/O on the same physical disk.

Resource contention problems have always been challenging to identify and to fix. Contention issues may come and go, only to return again when performance is most critical.

Here are the three basic steps for IT managers when it comes to resolving resource contention:

- First, IT needs to determine that the performance problems are indeed resource-related.

- Next, is to identify which transactions are competing for resources.

- Finally, to resolve the problem typically involves prioritizing one transaction above the other.

But which should you prioritize? This is a zero-sum game and one party will have to “lose” so ideally linking back to business priorities helps IT make informed decisions in the resolution process.

The Role of Virtualization in Resource Contention

With the advent of virtualization technology and cloud computing, however, resource contention is becoming harder to resolve.

First, there are new places where resource contention may occur. For example, CPU contention now comes in two forms: two processes racing for the same virtual machine CPU, and that virtual machine racing for physical CPU with other virtual machines. Another example is in storage pools, when data is competing for the fast but expensive Flash storage.

Second, environments are becoming more dynamic with virtualization and cloud technologies. As IT makes a transformation to IT-as-a-Service, new resources are constantly being provisioned and consumed. It is not uncommon to provision new VMs for hours with high workloads and then decommission these VMs when the load subsides. Mobile access and BYOD are other factors affecting the dynamic environment, since access patterns are changing and load is becoming less predictable.

Third, automation is a mixed blessing. The vendors of virtualization hardware and software are aware of the resource contention challenge and have introduced automatic algorithms to address it, which move workloads around to distribute the load more evenly and prioritize according to the load they are generating. This approach works well only if the busiest workloads are the most important ones. Yet this is not always the case, so the system prioritizes the less-important transactions at the expense of the more critical ones. Another implication of automation is that IT now has less visibility and less control of the environment.

Let’s revisit the steps for resolving resource contention, and factor in the impact of virtualization and cloud technologies:

1. Identify that the problem is related to resource contention

2. Identify the competitors

3. Prioritize the workloads according to business considerations

The first step is already problematic, since resource contention issues can manifest in any number of ways: what seems to be a large chunk of time spent in the Java tier may actually be a result of the Java VM not getting enough CPU.

The second step is even harder. Analysis of resource contention issues is after-the-fact. By then, the culprits may have already stopped competing, started using other resources or have been decommissioned altogether.

The third step is the hardest, since IT is hard-pressed to prioritize applications if they are unsure which processes/transactions/applications are competing.

Best Practices to Resolve Resource Contention in Virtual Environments

The number of possibilities for resource contention problems and ways to overcome them is substantial. Every IT organization has its own particular landscape and idiosyncrasies. Below, however, are some general guidelines which can be tailored to an organization’s unique needs.

The main considerations are the dynamic and multi-tier characteristics of resource contentions. An efficient approach must include cross-tier views, the ability to baseline and compare historical data and tying the resources to their business users:

Side-by-Side View of Performance Across Multiple Tiers: There are plenty of APM products and services that provide dashboards, but few of these solutions will perform complete end-to-end monitoring from the user’s end device to the storage disk, across physical and virtual infrastructure. To solve resource contention, you need to create a dashboard that collects and displays performance data curated from the various monitoring tools. This gives an indication of which resources are over-utilized and whether their over-utilization trend matches the workload trend of the tiers which access said resources. While not perfect, in a typical setting these matching trends would give you a big clue as to who’s using the resources and the resulting impact on performance.

Baselines and Reference Timeframes: When a performance problem occurs, IT should be able to compare the behavior of all components across the IT stack to their behavior in a previous reference timeframe or baseline. This will help you nail down what’s changed and, as a result, understand why a new performance problem has occurred.

Business Context of Performance: Integrating business context into performance metrics requires knowing, for each resource, which transactions are accessing that resource and when. Having the business context in each tier means that you can segregate performance according to the originating user calls and understand the business implications of each tier. Unfortunately, most APM tools have a technical focus today and do not connect the performance of individual tiers to the business transactions and implications. Hence you may need to technically enable passing some context or token between different tiers, for example by overriding the HTTP protocol between two JVMs to contain the original referring business transaction.

Beyond tools, there are needed changes to the IT culture and organization to ensure reliability and quality of service in cloud computing. The Cloud was supposed to break up the silos within IT, yet clearly those silos are still alive. It may take many years before the full transition to cloud and services-based IT forces down those walls.

What helps measurably for now, is if people from those different areas - the Java, network, database and storage tiers - are able to view the same data around infrastructure performance. Easily accessible and comprehensive data helps teams work together better because it eliminates any finger-pointing as to who should take the blame when users start to complain.

As with most problems in IT, teamwork with highly-skilled problem-solvers is still the best way to solve complex issues. Instead of shooting in the dark, it is time for IT departments to think proactively and strategically about how to resolve and manage resource contention, so that their companies can realize all the flexibility and productivity benefits of virtualization and cloud computing.

ABOUT Assaf Sagi

Assaf Sagi is Director of Product Management at Precise Software Solutions. He has more than 16 years of experience in enterprise software development and management. Prior to Precise, Assaf worked for IBM Research and for an advanced ComSec unit in the Israeli Defense Force.

Related Links:

www.precise.com

Share this

The Latest

October 14, 2021

Businesses are embracing artificial intelligence (AI) technologies to improve network performance and security, according to a new State of AIOps Study, conducted by ZK Research and Masergy ...

October 13, 2021

What may have appeared to be a stopgap solution in the spring of 2020 is now clearly our new workplace reality: It's impossible to walk back so many of the developments in workflow we've seen since then. The question is no longer when we'll all get back to the office, but how the companies that are lagging in their technological ability to facilitate remote work can catch up ...

October 12, 2021

The pandemic accelerated organizations' journey to the cloud to enable agile, on-demand, flexible access to resources, helping them align with a digital business's dynamic needs. We heard from many of our customers at the start of lockdown last year, saying they had to shift to a remote work environment, seemingly overnight, and this effort was heavily cloud-reliant. However, blindly forging ahead can backfire ...

October 07, 2021

SmartBear recently released the results of its 2021 State of Software Quality | Testing survey. I doubt you'll be surprised to hear that a "lack of time" was reported as the number one challenge to doing more testing, especially as release frequencies continue to increase. However, it was disheartening to see that a lack of time was also the number one response when we asked people to identify the biggest blocker to professional development ...

October 06, 2021

The role of the CIO is evolving with an increased focus on unlocking customer connections through service innovation, according to the 2021 Global CIO Survey. The study reveals the shift in the role of the CIO with the majority of CIO respondents stating innovation, operational efficiency, and customer experience as their top priorities ...

October 05, 2021

The perception of IT support has dramatically improved thanks to the successful response of service desks to the pandemic, lockdowns and working from home, according to new research from the Service Desk Institute (SDI), sponsored by Sunrise Software ...

October 04, 2021

Is your company trying to use artificial intelligence (AI) for business purposes like sales and marketing, finance or customer experience? If not, why not? If so, has it struggled to start AI projects and get them to work effectively? ...

September 30, 2021

As remote work persists, and organizations take advantage of hire-from-anywhere models — in addition to facing other challenges like extreme weather events — companies across industries are continuing to re-evaluate the effectiveness of their tech stack. Today's increasingly distributed workforce has put a much greater emphasis on network availability across more endpoints as well as increased the bandwidth required for voice and video. For many, this has posed the question of whether to switch to a new network monitoring system ...

September 29, 2021

When a website or app fails or falters, the standard operating procedure is to assemble a sizable team to quickly "divide and conquer" to find a solution. The details of the problem can usually be found somewhere among millions of log events and metrics, leading to slow and painstaking searches that can take hours and often involve handoffs between experts in different areas of the software. The immediate goal in these situations is not to be comprehensive, but rather to troubleshoot until you find a solution that remedies the symptom, even if the underlying root cause is not addressed ...

September 28, 2021

Evaluating which products and vendors can meet today's modern and complex IT business requirements is a challenge. To help, I'd like to explore 10 key questions every IT admin should be asking when evaluating or working with network performance tools ...