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https://issues.apache.org/jira/browse/KYLIN-5229?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaoxiang Yu updated KYLIN-5229:
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Attachment: image-2022-08-17-13-17-40-751.png
> PropertiesDelegate introduce lock to KylinConfig
> ------------------------------------------------
>
> Key: KYLIN-5229
> URL: https://issues.apache.org/jira/browse/KYLIN-5229
> Project: Kylin
> Issue Type: Sub-task
> Components: Metadata
> Reporter: Xiaoxiang Yu
> Priority: Major
> Fix For: 5.0-alpha
>
> Attachments: image-2022-08-17-13-17-40-751.png
>
>
> h2. Background
> Kylin 5.0 dev team plans to add new feature which supports reading config
> entry from external Config Server(such as Nacos) other than local
> kylin.properties. So we add {{PropertiesDelegate}} and
> {{IExternalConfigLoader}} to support this request.
> h2. Issue
> {{PropertiesDelegate }}introduces performance downgrade because it add lock
> to {{{}KylinConfigBase#getOptional{}}}, impact query concurrency badly, from
> Yanghong Team's load testing result, query concurrency change from 60 to 3.
> h2. Root Cause
>
> {code:java}
> protected String getOptional(String prop, String dft) {
> final String property = System.getProperty(prop);
> return property != null ? getSubstitutor().replace(property)
> : getSubstitutor().replace(properties.getProperty(prop, dft)); //
> Step 1
> }
>
> protected StrSubstitutor getSubstitutor() {
> // overrides > env > properties
> final Map<String, Object> all = Maps.newHashMap();
> all.putAll((Map) properties); // Step 2
> all.putAll(STATIC_SYSTEM_ENV);
> all.putAll(overrides);
> return new StrSubstitutor(all);
> }
> @Override
> public Set<Map.Entry<Object, Object>> entrySet() {
> return getAllProperties().entrySet(); // Step 3
> }
> private synchronized Properties getAllProperties() { // Step4, synchronized
>
> Properties propertiesView = new Properties();
> if (this.configLoader != null) {
> propertiesView.putAll(this.configLoader.getProperties());
> }
> propertiesView.putAll(this.properties);
> return propertiesView;
> } {code}
>
> h2. Screenshots
> Java Stack of Query Thread:
> !image-2022-08-17-13-16-25-721.png!
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