The Windows DLL loader lock: how a Rust thread can hang your JVM
The article discusses a deadlock issue encountered in a Windows CI pipeline involving Rust threads and the Java Virtual Machine (JVM). It details the investigation process that revealed how Rust's thread-local storage and the JVM's garbage collection mechanisms interacted to cause the hang. The authors provide insights into the debugging process and the technical intricacies of the Loader Lock in Windows.
- ▪A deadlock was discovered in a Windows CI pipeline that caused processes to freeze without a Java stack trace.
- ▪The issue arose during Rust's thread-local storage destruction, which interfered with the JVM's garbage collection process.
- ▪The authors used process dumps and thread analysis to identify the root cause of the hang.
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| Original publisher | QuestDB |
| Canonical URL | https://questdb.com/blog/windows-dll-loader-lock-rust-jni-deadlock/ |
| Publication time | Tue, 19 May 2026 04:50:49 -0500 |
| Retrieval time | 2026-05-19T10:04:57.575Z |
| Last seen | 2026-05-19T10:04:57.575Z |
| Headline source | Publisher (no WeSearch rewrite) |
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| Commercial reuse | May the content be reused commercially? | Not permitted |
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Opening excerpt (first ~120 words) tap to expand
The Windows DLL loader lock: how a Rust thread can hang your JVMRaphaël DalmonCore Database EngineerJaromir HamalaCore Database Engineer3 months agoTags:engineeringrustjavajniwindowsdebugging QuestDB is the open-source time-series database for demanding workloads—from trading floors to mission control. It delivers ultra-low latency, high ingestion throughput, and a multi-tier storage engine. Native support for Parquet and SQL keeps your data portable, AI-ready—no vendor lock-in. Introduction Several weeks ago, we encountered a silent, sporadic hang in our Windows CI pipeline. After a deep investigation, we uncovered a deadlock that left processes completely frozen with no ability to extract a Java stack trace.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at QuestDB.
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