8368089: G1: G1PeriodicGCTask::should_start_periodic_gc may use uninitialised value if os::loadavg is unsupported

[hgqxjj]

Please review this change. Thanks!

Description:

Previously the check combined loadavg() failure and threshold comparison in a single condition. When os::loadavg() returned -1, recent_load contained an undefined value but was still logged as if it was a real load average, leading to misleading log output.

Fix:

This change separates the failure case from the combined check:

• If os::loadavg() returns -1, log "System loadavg not supported" and skip.
• Only compare recent_load to the threshold when loadavg() succeeds.

Test:

GHA

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue

Issue

• JDK-8368089: G1: G1PeriodicGCTask::should_start_periodic_gc may use uninitialised value if os::loadavg is unsupported (Bug - P4)

Reviewing

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Webrevs

• 01: Full - Incremental (4ff7567c)
• 00: Full (a490606c)