github-actions[bot] commented on code in PR #69423:
URL: https://github.com/apache/doris/pull/69423#discussion_r4345214798
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fe/fe-core/src/main/java/org/apache/doris/common/DNSCache.java:
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@@ -57,7 +59,27 @@ public void start() {
* @return The IP address for the given hostname.
*/
public String get(String hostname) {
- return cache.computeIfAbsent(hostname, this::resolveHostname);
+ String cachedIp = cache.get(hostname);
+ if (cachedIp != null && !refreshPending.contains(hostname)) {
+ return cachedIp;
+ }
+ return cache.compute(hostname, (host, currentIp) -> {
+ // Claim before DNS I/O so an invalidation arriving during this
lookup is
+ // retained for the next get(). Concurrent lookups of this host
serialize here.
+ boolean needsRefresh = refreshPending.remove(host);
+ if (currentIp == null || needsRefresh) {
+ return resolveHostname(host);
+ }
+ return currentIp;
+ });
+ }
+
+ public void invalidate(String hostname) {
+ // A successful heartbeat may coincide with a temporary DNS outage.
Keep the
+ // last known IP so resolveHostname can fall back instead of caching
an empty IP.
+ if (cache.containsKey(hostname)) {
Review Comment:
[P2] Preserve invalidation during the first hostname lookup
If a query is inside the first `get(hostname)` DNS computation when a
successful restart heartbeat (or its replay) calls this method, the cache entry
has not been published, so `containsKey` is false and the refresh request is
lost. That earlier lookup can then publish the old pod IP and create a channel
after `invalidateForAll` has finished. Subsequent queries take the unmarked
cache fast path and keep connecting to the obsolete IP until the periodic
refresh (60 seconds, with a 120-second initial delay). Retain invalidation for
in-flight first lookups, for example with a pending marker or generation, and
cover this ordering with a latch-controlled test. This is distinct from the
existing fallback-retention thread: here no cached IP exists when invalidation
arrives.
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