project/info: cgroup v2 compatibility

Author: haraldschilly

src/CLAUDE.md

@@ -20,6 +20,7 @@ This file provides guidance to Claude Code (claude.ai/code) and also Gemini CLI
 - Some older code is JavaScript or CoffeeScript, which will be translated to TypeScript
 - Use ES modules (import/export) syntax, not CommonJS (require)
 - Organize the list of imports in such a way: installed npm packages are on top, newline, then are imports from @cocalc's code base. Sorted alphabetically.
+- **Backend Logging**: Use `getLogger` from `@cocalc/project/logger` for logging in backend code. Do NOT use `console.log`. Example: `const L = getLogger("module:name").debug;`
 
 ## Development Commands
 

src/packages/comm/project-status/utils.ts

@@ -8,13 +8,28 @@ import type {
   DiskUsageInfo,
 } from "@cocalc/util/types/project-info/types";
 
-// DiskUsage for /tmp !
+/**
+ * Calculate resource usage statistics from cgroup data.
+ *
+ * This function processes cgroup resource information and calculates usage percentages
+ * for both memory and CPU. It works with both cgroup v1 and v2 data structures,
+ * handling the unified CGroup interface that abstracts the differences between versions.
+ */
 export function cgroup_stats(cg: CGroup, du?: DiskUsageInfo) {
-  // why? /tmp is a memory disk in kucalc
+  // DiskUsage for /tmp – add to memory usage since it's already been
+  // calculated appropriately by the backend based on whether /tmp is tmpfs
   const mem_rss = cg.mem_stat.total_rss + (du?.usage ?? 0);
   const mem_tot = cg.mem_stat.hierarchical_memory_limit;
-  const mem_pct = 100 * Math.min(1, mem_rss / mem_tot);
-  const cpu_pct = 100 * Math.min(1, cg.cpu_usage_rate / cg.cpu_cores_limit);
+
+  // Handle unlimited (-1) and zero memory limits to avoid division by zero
+  const mem_pct = mem_tot <= 0 ? 0 : 100 * Math.min(1, mem_rss / mem_tot);
+
+  // Handle unlimited (-1) and zero CPU limits to avoid division by zero
+  const cpu_pct =
+    cg.cpu_cores_limit <= 0
+      ? 0
+      : 100 * Math.min(1, cg.cpu_usage_rate / cg.cpu_cores_limit);
+
   const cpu_tot = cg.cpu_usage; // seconds
   return { mem_rss, mem_tot, mem_pct, cpu_pct, cpu_tot };
 }