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  • Spawning a New Process for Socket-Activated Daemons is Error-Prone

    calendar Dec 10, 2025 · 4 min read · Linux systemd Container  ·
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    I recently debugged a mysterious latency issue: after migrating a systemd service from path-activation to socket-activation, there was a consistent ~1 second time-to-available latency. The culprit was a bad practice—starting the daemon program as a new process in socket-activation. Let's dive into the details. Starting …


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  • Be careful making thread-aware syscalls in Go: lock the thread

    calendar Oct 20, 2025 · 10 min read · Go Container Linux  ·
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    A bug caused around 0.5% of container workloads to fail to start during load test. This post walks through the bug and its fix, an interesting mix of Linux namespaces, Go concurrency, and syscalls. The need to run a program in its own network namespace and mount namespace soci-snapshotter is an open-source containerd …


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  • Mysterious Image Pull Failures: "401 Unauthorized" and "Not Found" After Migrating Containerd to v2

    calendar Oct 12, 2025 · 7 min read · container AWS  ·
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    Early this year, we migrated containerd from v1.7 to v2.0.5. However, we quickly noticed image pulls from Amazon Elastic Container Registry (ECR) began failing for both public and private ECR repositories. For example: 1# public ECR 2FATA[0031] failed to resolve reference …


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  • x509: certificate signed by unknown authority? Maybe the cert pool is empty

    calendar Apr 15, 2025 · 6 min read · Linux Container SELinux Bottlerocket  ·
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    I recently worked on getting amazon-ssm-agent to run inside containers on Bottlerocket. During that process, I ran into a TLS issue connecting to amazonaws.com. The root cause turned out be interesting and we'll walk through it in this post. Running amazon-ssm-agent in a container: why and how? To enable sessions …


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  • Missing Container Disk I/O Stats with cgroup v1 on Kernel 6.1

    calendar Nov 9, 2024 · 4 min read · Linux Container  ·
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    As Amazon Linux 2 (AL2) approaches its End of Life on June 30, 2025, we have started migrating our container platform from AL2 to Bottlerocket. The migration encountered a few speed bumps. In this post, we'll examine one of them: missing container disk I/O stats. Why are container I/O dashboards blank? Since …


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Peng Zhang

Software Engineer

Recent Posts

  • Who killed my service: collecting kernel kill logs with OTEL
  • Avoid using 2D map for transition table in Go
  • cached-imds-client: cache static IMDS responses to improve robustness
  • Using WaitGroup to Track Work Items, Not Workers: A Multi-threaded BFS Example
  • Simplify device path on boot with udev
  • Use KillMode=process with caution: restart loop could deplete resources
  • Spawning a New Process for Socket-Activated Daemons is Error-Prone
  • Be careful making thread-aware syscalls in Go: lock the thread

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