PyCharm internal HTTP client versus JVM DNS resolver: default cache ownership

Question

Goal
Determine whether PyCharm’s bundled Java HttpClient resolves VCS and plugin-update hostnames exclusively through the JVM/OS resolver, or whether the IDE maintains a separate DNS cache that can return stale entries after network changes.
Constraints and uncertainty
PyCharm documentation does not state which resolver owns hostname lookups for Git over HTTPS and plugin updates. The Help menu’s “Clear DNS cache” action does not clarify whether it clears an IDE-specific cache, the JVM cache, or both. Behavior may also differ between Community and Professional editions and across Windows, macOS, and Linux because the bundled JVM handles networking differently by platform.
Assume a current PyCharm release using its default bundled JVM and no custom trust-store environment variables.
Questions

Does PyCharm rely exclusively on the JVM/OS DNS resolver for internal HTTP client operations?
If the IDE keeps its own DNS cache, what is its default TTL and is it shared across plugin updates and Git over HTTPS?
Which cache does “Clear DNS cache” affect, and does clearing it force a new JVM-level resolution?

Tasadduq Burney · Answer

Direct answer
PyCharm does not rely exclusively on the JVM/OS resolver for every internal hostname lookup. Resolution ultimately passes through java.net.InetAddress and the operating system resolver, but the IntelliJ Platform layer beneath PyCharm can maintain a separate short-lived in-memory DNS cache for IDE HTTP client traffic. Git over HTTPS normally uses JGit over standard JVM URL and HttpClient code, so it is governed by the JVM InetAddress cache and the OS resolver, not by the IDE cache.
Confirmed facts

PyCharm runs on its bundled JVM; all hostname resolution eventually delegates to java.net.InetAddress and the OS resolver. The IDE does not replace the OS resolver.
The bundled JVM is configured with short values for networkaddress.cache.ttl and networkaddress.cache.negative.ttl; the exact seconds depend on the release and should be read from the running process.
Help → Clear DNS Cache clears the IDE-owned in-memory DNS cache only. It does not clear the JVM InetAddress cache or the OS resolver cache, and it does not by itself force a new JVM-level resolution.

Likely behavior requiring verification

The IDE DNS cache is likely shared across plugin updates and other IDE internal HTTP requests, but it is not shared with JGit transports or external tools launched by PyCharm.
Default TTL and cache presence vary by PyCharm version, edition, and operating system; treat the cache TTL as unknown until confirmed in idea.log or IDE properties.

Verification steps for this case

Open Help → About, copy the IDE properties, and check networkaddress.cache.ttl and networkaddress.cache.negative.ttl for the running bundled JVM.
Use Help → Clear DNS Cache, then trigger a plugin update and watch idea.log for DNS resolution messages to see whether the IDE cache is bypassed.
Change a test hostname mapping in the OS hosts file or local resolver, restart PyCharm, and compare resolution timing for plugin updates versus a Git over HTTPS fetch to infer which layer is stale.

Missing diagnostic detail
Does the stale hostname affect both plugin updates and Git over HTTPS, or only one of them? This determines whether the issue belongs in the IDE cache, the JVM TTL, or the OS resolver.
Assumption: current PyCharm release using the default bundled JVM with no custom trust-store or network JVM options. Behavior is version- and platform-sensitive; verify on the affected installation before applying changes.

PyCharm internal HTTP client versus JVM DNS resolver: default cache ownership

Goal

Constraints and uncertainty

Questions

1 answer

Direct answer

Confirmed facts

Likely behavior requiring verification

Verification steps for this case

Missing diagnostic detail

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