Fixing Memory Leaks From Hidden ETW Sessions EtwD EtwB EtwR

by StackCamp Team 60 views

Have you ever encountered a situation where your system's memory seems to be mysteriously disappearing, despite Task Manager and RamMap showing no obvious culprits? You might be facing a memory leak caused by Event Tracing for Windows (ETW) sessions. This article delves into the intricacies of ETW-related memory leaks, focusing on scenarios where these sessions, often named EtwD, EtwB, and EtwR, run silently in the background, consuming resources without being readily visible. We'll explore how to identify, diagnose, and ultimately fix these elusive memory leaks to restore your system's performance and stability.

Identifying the Culprit: ETW Sessions and Memory Leaks

ETW (Event Tracing for Windows) is a powerful built-in tracing facility in the Windows operating system. It allows developers and administrators to log system events for debugging, performance analysis, and monitoring purposes. While invaluable for troubleshooting, ETW sessions can sometimes lead to memory leaks if not properly managed. These leaks often manifest when ETW sessions are started but not stopped correctly, or when they are configured to capture excessive data. The challenge lies in the fact that these sessions might not always appear prominently in standard monitoring tools like Task Manager or RamMap, making them difficult to detect.

When an ETW session leaks memory, it essentially means that the session is allocating memory but not releasing it back to the system. Over time, this can lead to a significant depletion of available memory, causing performance degradation, application crashes, and even system instability. The most common ETW session names associated with these leaks are EtwD, EtwB, and EtwR, although the specific names may vary depending on the software or drivers involved. To effectively tackle these memory leaks, it's crucial to understand how ETW sessions work, how they can consume memory, and how to identify and manage them.

Diagnosing ETW-Related Memory Leaks

Diagnosing ETW-related memory leaks requires a combination of tools and techniques. Since Task Manager and RamMap might not always reveal the extent of the problem, we need to dig deeper using more specialized tools. Here’s a step-by-step approach to diagnosing these leaks:

1. Performance Monitor (PerfMon)

Performance Monitor is a powerful built-in Windows tool that allows you to track various system metrics, including memory usage by individual processes and ETW sessions. To use PerfMon for diagnosing ETW leaks:

  • Open Performance Monitor by searching for “perfmon” in the Start Menu.
  • In the left pane, expand “Data Collector Sets” and then “Event Trace Sessions.”
  • You should see a list of running ETW sessions, including EtwD, EtwB, and EtwR, if they are active.
  • Right-click on a suspicious session and select “Properties.”
  • In the “Properties” window, you can review the session's configuration, including the providers it's tracing and the events it's capturing. This can give you clues about the session's purpose and potential impact on memory usage.
  • To monitor memory usage, add the “Memory\Pool Nonpaged Bytes” and “Memory\Pool Paged Bytes” counters for the specific ETW session. This will show you how much kernel memory the session is consuming.

2. Windows Performance Analyzer (WPA)

WPA is a free tool from Microsoft that provides advanced performance analysis capabilities. It's particularly useful for analyzing ETW traces and identifying memory leaks. To use WPA:

  • Download and install the Windows Assessment and Deployment Kit (ADK), which includes WPA.
  • Use the wpr command-line tool to start an ETW tracing session. For example, you can use wpr -start GeneralProfile -filemode to start a general-purpose tracing session.
  • Reproduce the memory leak issue while the tracing session is running.
  • Stop the tracing session using wpr -stop -resultPath <path_to_trace_file>. Replace <path_to_trace_file> with the desired location for the trace file.
  • Open the trace file in WPA.
  • Use WPA’s analysis features to identify memory allocations and deallocations by ETW sessions. Look for patterns of memory allocation without corresponding deallocations, which indicates a leak.

3. PoolMon

PoolMon is a command-line tool that monitors kernel-mode memory allocations, which is where ETW sessions often allocate memory. It can help pinpoint the specific memory pools that are leaking. To use PoolMon:

  • Open a command prompt as an administrator.
  • Type poolmon.exe and press Enter.
  • PoolMon will display a list of memory pools and their usage.
  • Press “B” to sort by bytes, which will show the pools with the highest memory consumption at the top.
  • Look for pool tags associated with ETW or the drivers and applications you suspect are involved in the leak.

4. Process Explorer

Process Explorer, a free tool from Sysinternals, provides a detailed view of processes running on your system, including their memory usage and handles. While it might not directly show ETW session memory usage, it can help identify processes that are starting and managing these sessions.

  • Download and run Process Explorer as an administrator.
  • Look for processes that are related to ETW, such as svchost.exe instances hosting the Event Log service, or specific applications that use ETW for logging.
  • Examine the process's properties, including its memory usage and open handles. This can help you understand which processes are involved in ETW session management.

By combining these tools and techniques, you can gain a comprehensive understanding of ETW session memory usage and identify the specific sessions that are leaking memory.

Fixing ETW-Related Memory Leaks

Once you've identified the ETW sessions causing memory leaks, the next step is to fix the underlying issues. The specific steps required to fix a leak will depend on the cause, but here are some general strategies:

1. Stop Unnecessary ETW Sessions

The most straightforward way to address an ETW memory leak is to stop the problematic session. You can do this using Performance Monitor, the logman command-line tool, or the application that started the session. To stop a session using logman:

  • Open a command prompt as an administrator.
  • Type logman stop <session_name> and press Enter. Replace <session_name> with the name of the ETW session, such as EtwD, EtwB, or EtwR.

Before stopping a session, make sure you understand its purpose and whether stopping it will affect any critical system functions or applications. If you're unsure, it's best to consult the documentation for the software that started the session or contact the software vendor for support.

2. Configure ETW Sessions Properly

If you need to keep an ETW session running, you can reduce its memory footprint by configuring it properly. This involves limiting the amount of data the session captures and ensuring that it's stopped when no longer needed. Here are some configuration tips:

  • Reduce the number of providers: Only enable tracing for the providers you need to monitor. Disabling unnecessary providers will reduce the amount of data the session captures and the memory it consumes.
  • Filter events: Use filters to capture only the events you're interested in. This can significantly reduce the amount of data logged by the session.
  • Limit the buffer size: ETW sessions use buffers to store events before writing them to disk. Limiting the buffer size can prevent the session from consuming excessive memory. However, setting the buffer size too low can lead to dropped events, so it's important to strike a balance.
  • Use circular logging: Circular logging allows ETW sessions to overwrite older events when the buffer is full. This prevents the session from growing indefinitely and consuming all available memory.
  • Stop sessions when not needed: Ensure that ETW sessions are stopped when they're no longer needed. This is especially important for sessions started by applications, which might not be automatically stopped when the application exits.

3. Update Drivers and Software

Memory leaks in ETW sessions can sometimes be caused by bugs in drivers or software that use ETW. Updating to the latest versions of drivers and software can often fix these bugs and resolve the leaks. Check for updates for your graphics drivers, network drivers, and any other drivers or software that might be involved in ETW tracing.

4. Identify and Fix the Root Cause

In some cases, ETW memory leaks are a symptom of a deeper problem in the system or an application. To fully resolve the issue, it's important to identify and fix the root cause. This might involve debugging the application, analyzing system logs, or consulting with the software vendor. If you suspect a specific application or driver is causing the leak, try disabling it temporarily to see if the leak disappears. This can help you narrow down the source of the problem.

5. Monitor and Maintain Your System

After fixing an ETW memory leak, it's important to monitor your system to ensure that the issue doesn't return. Regularly check memory usage and ETW session activity using the tools and techniques described earlier. You can also set up alerts to notify you if memory usage exceeds certain thresholds. By proactively monitoring your system, you can prevent future memory leaks and maintain optimal performance.

Practical Examples and Scenarios

To illustrate how these techniques can be applied in real-world scenarios, let's consider a few examples:

Scenario 1: High Memory Usage by EtwD Session

You notice that the EtwD session is consuming a significant amount of memory, even when the system is idle. Using Performance Monitor, you find that the session is capturing events from several providers, including some that are not relevant to your current troubleshooting efforts. To fix this:

  • Open Performance Monitor and navigate to “Data Collector Sets\Event Trace Sessions.”
  • Right-click on the EtwD session and select “Properties.”
  • In the “Providers” tab, disable the providers that are not needed.
  • In the “Advanced” tab, configure circular logging to prevent the session from growing indefinitely.

Scenario 2: Memory Leak After Running a Specific Application

You observe a memory leak that occurs after running a particular application. Using WPA, you trace the application's activity and find that it's starting an ETW session but not stopping it when the application exits. To fix this:

  • Contact the application vendor and report the issue. They may be able to provide a fix or workaround.
  • As a temporary solution, create a script or scheduled task to stop the ETW session after the application exits.

Scenario 3: Driver-Related ETW Leak

You suspect that a device driver is causing an ETW memory leak. Using PoolMon, you identify a pool tag associated with the driver that's consuming a large amount of memory. To fix this:

  • Update the driver to the latest version.
  • If updating the driver doesn't fix the issue, contact the device manufacturer and report the problem.

Conclusion

ETW memory leaks can be challenging to diagnose and fix, but by understanding how ETW works and using the right tools and techniques, you can effectively address these issues. By identifying the leaking sessions, configuring them properly, updating drivers and software, and monitoring your system, you can prevent memory leaks and maintain optimal system performance. Remember to always consider the potential impact of stopping or modifying ETW sessions, and consult with experts or vendors when necessary. Addressing these often-hidden memory consumers not only optimizes system resources but also contributes to a more stable and responsive computing environment.

By following the strategies outlined in this article, you can confidently tackle ETW-related memory leaks and ensure your system runs smoothly and efficiently. Regular maintenance and monitoring are key to preventing future occurrences and maintaining a healthy computing environment.