OOM in the middle of a DNS query

Oct 13, 2025 by wbrum.org 55 views

Introduction

When it comes to .NET Core applications, crashes can be a significant concern. One such crash that has been observed is the Out of Memory (OOM) crash during a DNS query. In this article, we will delve into the details of this issue, explore the possible causes, and discuss potential solutions to prevent such crashes.

Description

The crash in question is characterized by the following stack trace:

<oom throw>
coreclr!JIT_NewArr1+0x517 [D:\a\_work\1\s\src\coreclr\vm\jithelpers.cpp @ 2801]
System_Net_NameResolution!System.Net.NameResolutionPal.ParseAddressInfoEx+0x0 [/_/src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Windows.cs @ 316]
System_Net_NameResolution!System.Net.NameResolutionPal.ProcessResult+0x0 [/_/src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Windows.cs @ 203]
System_Net_NameResolution!System.Net.NameResolutionPal.GetAddressInfoExCallback+0x21 [/_/src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Windows.cs @ 183]
<ws2_32 callback from the windows threadpool>

This crash occurs when the .NET Core runtime encounters an Out of Memory exception while processing a DNS query. The question remains whether this is something that the runtime should handle gracefully or if OOM crashes are unavoidable in general.

Reproduction Steps

To reproduce this issue, you can follow these steps:

OOM in the middle of a DNS query: The crash occurs when the .NET Core runtime runs out of memory while processing a DNS query.

Expected Behavior

The expected behavior in this scenario is for the task to fault instead of resulting in an unhandleable exception.

Actual Behavior

However, the actual behavior is an unhandled crash, which can lead to application downtime and data loss.

Regression

There is no response regarding whether this issue is a regression or not.

Known Workarounds

There are no known workarounds for this issue.

Configuration

There is no additional configuration information available for this issue.

Other Information

There is no other relevant information available for this issue.

OOM Crashes: Are They Avoidable?

OOM crashes can be a significant concern for .NET Core applications. While it is possible to handle some OOM exceptions, others may be unavoidable. In the case of the DNS query crash, it is unclear whether the runtime should handle it gracefully or if it is an unavoidable consequence of running out of memory.

Potential Solutions

To prevent OOM crashes during DNS queries, several potential solutions can be explored:

Memory Profiling: Conducting memory profiling can help identify memory leaks and optimize the application's memory usage.
Garbage Collection: Ensuring that the garbage collector is running regularly can help free up memory and prevent OOM crashes.
DNS Query Optimization: Optimizing DNS queries can reduce the memory requirements and prevent OOM crashes.
OOM Handling: Implementing OOM handling mechanisms can help the application recover from OOM crashes and prevent data loss.

Conclusion

OOM crashes during DNS queries can be a significant concern for .NET Core applications. While it is unclear whether the runtime should handle it gracefully or if it is an unavoidable consequence of running out of memory, several potential solutions can be explored to prevent such crashes. By conducting memory profiling, optimizing DNS queries, and implementing OOM handling mechanisms, developers can help prevent OOM crashes and ensure the reliability of their applications.

Recommendations

Based on the analysis of this issue, the following recommendations can be made:

Conduct Memory Profiling: Conducting memory profiling can help identify memory leaks and optimize the application's memory usage.
Optimize DNS Queries: Optimizing DNS queries can reduce the memory requirements and prevent OOM crashes.
Implement OOM Handling: Implementing OOM handling mechanisms can help the application recover from OOM crashes and prevent data loss.
Monitor Application Performance: Monitoring application performance can help identify potential issues before they lead to OOM crashes.

Q: What is an Out of Memory (OOM) crash?

A: An Out of Memory (OOM) crash occurs when a .NET Core application runs out of memory and is unable to allocate additional memory to continue executing. This can lead to a crash and potentially result in data loss.

Q: What causes an OOM crash during a DNS query?

A: An OOM crash during a DNS query can be caused by a variety of factors, including:

Memory leaks: Memory leaks occur when an application fails to release memory that it has allocated, leading to a gradual increase in memory usage over time.
DNS query optimization: DNS queries can be optimized to reduce the memory requirements, but if not optimized properly, it can lead to OOM crashes.
OOM handling: OOM handling mechanisms can help the application recover from OOM crashes and prevent data loss.

Q: Can OOM crashes be avoided?

A: While it is possible to handle some OOM exceptions, others may be unavoidable. In the case of the DNS query crash, it is unclear whether the runtime should handle it gracefully or if it is an unavoidable consequence of running out of memory.

Q: What are some potential solutions to prevent OOM crashes during DNS queries?

A: Some potential solutions to prevent OOM crashes during DNS queries include:

Memory profiling: Conducting memory profiling can help identify memory leaks and optimize the application's memory usage.
Garbage collection: Ensuring that the garbage collector is running regularly can help free up memory and prevent OOM crashes.
DNS query optimization: Optimizing DNS queries can reduce the memory requirements and prevent OOM crashes.
OOM handling: Implementing OOM handling mechanisms can help the application recover from OOM crashes and prevent data loss.

Q: How can I monitor my application's performance to prevent OOM crashes?

A: To monitor your application's performance and prevent OOM crashes, you can use various tools and techniques, including:

Memory profiling tools: Tools such as Visual Studio's Memory Profiler or dotMemory can help identify memory leaks and optimize the application's memory usage.
Performance counters: Performance counters can provide insights into the application's memory usage and help identify potential issues before they lead to OOM crashes.
Logging and monitoring: Logging and monitoring can help identify potential issues and provide insights into the application's performance.

Q: What are some best practices for preventing OOM crashes during DNS queries?

A: Some best practices for preventing OOM crashes during DNS queries include:

Optimize DNS queries: Optimize DNS queries to reduce the memory requirements and prevent OOM crashes.
Implement OOM handling: Implement OOM handling mechanisms to help the application recover from OOM crashes and prevent data loss.
Monitor application performance: Monitor application performance to identify potential issues before they lead to OOM crashes.
Conduct regular memory profiling: Conduct regular memory profiling to identify memory leaks and optimize the application's memory usage.

Q: Can I share a Watson bucket to help diagnose the issue?

A: Yes, you can share a Watson bucket to help diagnose the issue. This can provide valuable insights into the application's performance and help identify potential issues that may be contributing to the OOM crash.

Q: What are some additional resources that can help me prevent OOM crashes during DNS queries?

A: Some additional resources that can help you prevent OOM crashes during DNS queries include:

Microsoft documentation: Microsoft documentation provides detailed information on how to prevent OOM crashes during DNS queries.
.NET Core documentation: .NET Core documentation provides detailed information on how to prevent OOM crashes during DNS queries.
Third-party tools and libraries: Third-party tools and libraries can provide additional insights and help identify potential issues that may be contributing to the OOM crash.

By following these best practices and using the resources provided, you can help prevent OOM crashes during DNS queries and ensure the reliability of your application.