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Introduce retries when pinging servers. #155

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Feb 3, 2025
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Introduce retries when pinging servers. #155

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8f0f42d
Introduce retries when pinging servers.
Dec 6, 2024
100e7c3
Changes:
Dec 9, 2024
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35 changes: 32 additions & 3 deletions evcache-core/src/main/java/com/netflix/evcache/pool/EVCacheClientPool.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1173,9 +1173,38 @@ public void pingServers() {
for (Entry<ServerGroup, List<EVCacheClient>> entry : allServers.entrySet()) {
final List<EVCacheClient> listOfClients = entry.getValue();
for (EVCacheClient client : listOfClients) {
final Map<SocketAddress, String> versions = client.getVersions();
for (Entry<SocketAddress, String> vEntry : versions.entrySet()) {
if (log.isDebugEnabled()) log.debug("Host : " + vEntry.getKey() + " : " + vEntry.getValue());

int maxRetries = 10;
long retryDelayMs = 1000;
for (int i = 0; i < maxRetries; i++) {
final Map<SocketAddress, String> versions = client.getVersions();
boolean allNodesOk = true;

for (Entry<SocketAddress, String> vEntry : versions.entrySet()) {
String version = vEntry.getValue();
// Only accept version in format like "1.6.15"
if (!version.matches("\\d+\\.\\d+\\.\\d+")) {
allNodesOk = false;
log.warn("Node not ready or invalid version: {}, response: {}, attempt {}",
vEntry.getKey(), version, i + 1);
break;
}
}

if (allNodesOk) {
if (log.isDebugEnabled()) {
for (Entry<SocketAddress, String> vEntry : versions.entrySet()) {
log.debug("Host : {} Version : {}", vEntry.getKey(), vEntry.getValue());
}
}
break;
}

if (i < maxRetries - 1) {
Thread.sleep(retryDelayMs);
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This would block for 10 seconds per node during startup, which could be a very long time and would prevent application startup. I think we should aim to do this asynchronously or some other way.

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true, it can block for o(seconds). I've few more thoughts. I will share them shortly.

} else {
log.error("Some nodes not ready after max retries for client: {}", client);
}
}
}
}
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