Code reviewHardcr-g235

Subject Thread safetyLevel Senior–Staff~40 minCommon in Concurrency interviewsIndustries Software development

Question

Review this Java holder that publishes an object through a non-volatile field.

Assume `initOnce()` runs exactly once, before readers are told to start. Is unsynchronized publication safe here?

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Code to reviewjava

1class Holder {2    private Resource res;                 // not volatile, not final3 4    void initOnce() {                     // called by one init thread5        Resource r = new Resource();6        r.setup();                        // sets internal fields7        this.res = r;                     // (1) publish8    }9    Resource getResource() {              // called by many reader threads10        return res;                       // (2) read without sync11    }12}

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