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Batch Async Fetcher class changes (opensearch-project#8742)
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* Async Fetcher class changes

Signed-off-by: Gaurav Chandani <[email protected]>
Signed-off-by: Shivansh Arora <[email protected]>
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@Gaurav614 @shiv0408
Gaurav614 authored and shiv0408 committed Apr 25, 2024
1 parent 462d9f8 commit 8126c0c
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Showing 9 changed files with 291 additions and 76 deletions.
6 changes: 3 additions & 3 deletions ...in/java/org/opensearch/action/admin/indices/shards/TransportIndicesShardStoresAction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -195,7 +195,7 @@ void start() {
} else {
for (Tuple<ShardId, String> shard : shards) {
InternalAsyncFetch fetch = new InternalAsyncFetch(logger, "shard_stores", shard.v1(), shard.v2(), listShardStoresInfo);
fetch.fetchData(nodes, Collections.<String>emptySet());
fetch.fetchData(nodes, Collections.emptyMap());
}
}
}
Expand Down Expand Up @@ -223,7 +223,7 @@ protected synchronized void processAsyncFetch(
List<FailedNodeException> failures,
long fetchingRound
) {
fetchResponses.add(new Response(shardId, responses, failures));
fetchResponses.add(new Response(shardAttributesMap.keySet().iterator().next(), responses, failures));
if (expectedOps.countDown()) {
finish();
}
Expand Down Expand Up @@ -312,7 +312,7 @@ private boolean shardExistsInNode(final NodeGatewayStartedShards response) {
}

@Override
protected void reroute(ShardId shardId, String reason) {
protected void reroute(String shardId, String reason) {
// no-op
}

Expand Down
140 changes: 103 additions & 37 deletions server/src/main/java/org/opensearch/gateway/AsyncShardFetch.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@
import org.opensearch.core.action.ActionListener;
import org.opensearch.core.concurrency.OpenSearchRejectedExecutionException;
import org.opensearch.core.index.shard.ShardId;
import org.opensearch.indices.store.ShardAttributes;
import org.opensearch.transport.ReceiveTimeoutTransportException;

import java.util.ArrayList;
Expand All @@ -54,12 +55,11 @@
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

import static java.util.Collections.emptySet;
import static java.util.Collections.unmodifiableSet;
import static java.util.Collections.emptyMap;
import static java.util.Collections.unmodifiableMap;

/**
* Allows to asynchronously fetch shard related data from other nodes for allocation, without blocking
Expand All @@ -69,6 +69,7 @@
* and once the results are back, it makes sure to schedule a reroute to make sure those results will
* be taken into account.
*
* It comes in two modes, to single fetch a shard or fetch a batch of shards.
* @opensearch.internal
*/
public abstract class AsyncShardFetch<T extends BaseNodeResponse> implements Releasable {
Expand All @@ -77,18 +78,21 @@ public abstract class AsyncShardFetch<T extends BaseNodeResponse> implements Rel
* An action that lists the relevant shard data that needs to be fetched.
*/
public interface Lister<NodesResponse extends BaseNodesResponse<NodeResponse>, NodeResponse extends BaseNodeResponse> {
void list(ShardId shardId, @Nullable String customDataPath, DiscoveryNode[] nodes, ActionListener<NodesResponse> listener);
void list(Map<ShardId, ShardAttributes> shardAttributesMap, DiscoveryNode[] nodes, ActionListener<NodesResponse> listener);

}

protected final Logger logger;
protected final String type;
protected final ShardId shardId;
protected final String customDataPath;
protected final Map<ShardId, ShardAttributes> shardAttributesMap;
private final Lister<BaseNodesResponse<T>, T> action;
private final Map<String, NodeEntry<T>> cache = new HashMap<>();
private final Set<String> nodesToIgnore = new HashSet<>();
private final AtomicLong round = new AtomicLong();
private boolean closed;
private final String reroutingKey;
private final Map<ShardId, Set<String>> shardToIgnoreNodes = new HashMap<>();

private final boolean enableBatchMode;

@SuppressWarnings("unchecked")
protected AsyncShardFetch(
Expand All @@ -100,9 +104,36 @@ protected AsyncShardFetch(
) {
this.logger = logger;
this.type = type;
this.shardId = Objects.requireNonNull(shardId);
this.customDataPath = Objects.requireNonNull(customDataPath);
shardAttributesMap = new HashMap<>();
shardAttributesMap.put(shardId, new ShardAttributes(shardId, customDataPath));
this.action = (Lister<BaseNodesResponse<T>, T>) action;
this.reroutingKey = "ShardId=[" + shardId.toString() + "]";
enableBatchMode = false;
}

/**
* Added to fetch a batch of shards from nodes
*
* @param logger Logger
* @param type type of action
* @param shardAttributesMap Map of {@link ShardId} to {@link ShardAttributes} to perform fetching on them a
* @param action Transport Action
* @param batchId For the given ShardAttributesMap, we expect them to tie with a single batch id for logging and later identification
*/
@SuppressWarnings("unchecked")
protected AsyncShardFetch(
Logger logger,
String type,
Map<ShardId, ShardAttributes> shardAttributesMap,
Lister<? extends BaseNodesResponse<T>, T> action,
String batchId
) {
this.logger = logger;
this.type = type;
this.shardAttributesMap = shardAttributesMap;
this.action = (Lister<BaseNodesResponse<T>, T>) action;
this.reroutingKey = "BatchID=[" + batchId + "]";
enableBatchMode = true;
}

@Override
Expand Down Expand Up @@ -130,11 +161,32 @@ public synchronized int getNumberOfInFlightFetches() {
* The ignoreNodes are nodes that are supposed to be ignored for this round, since fetching is async, we need
* to keep them around and make sure we add them back when all the responses are fetched and returned.
*/
public synchronized FetchResult<T> fetchData(DiscoveryNodes nodes, Set<String> ignoreNodes) {
public synchronized FetchResult<T> fetchData(DiscoveryNodes nodes, Map<ShardId, Set<String>> ignoreNodes) {
if (closed) {
throw new IllegalStateException(shardId + ": can't fetch data on closed async fetch");
throw new IllegalStateException(reroutingKey + ": can't fetch data on closed async fetch");
}
nodesToIgnore.addAll(ignoreNodes);

if (enableBatchMode == false) {
// we will do assertions here on ignoreNodes
if (ignoreNodes.size() > 1) {
throw new IllegalStateException(
"Fetching Shard Data, " + reroutingKey + "Can only have atmost one shard" + "for non-batch mode"
);
}
if (ignoreNodes.size() == 1) {
if (shardAttributesMap.containsKey(ignoreNodes.keySet().iterator().next()) == false) {
throw new IllegalStateException("Shard Id must be same as initialized in AsyncShardFetch. Expecting = " + reroutingKey);
}
}
}

// add the nodes to ignore to the list of nodes to ignore for each shard
for (Map.Entry<ShardId, Set<String>> ignoreNodesEntry : ignoreNodes.entrySet()) {
Set<String> ignoreNodesSet = shardToIgnoreNodes.getOrDefault(ignoreNodesEntry.getKey(), new HashSet<>());
ignoreNodesSet.addAll(ignoreNodesEntry.getValue());
shardToIgnoreNodes.put(ignoreNodesEntry.getKey(), ignoreNodesSet);
}

fillShardCacheWithDataNodes(cache, nodes);
List<NodeEntry<T>> nodesToFetch = findNodesToFetch(cache);
if (nodesToFetch.isEmpty() == false) {
Expand All @@ -153,7 +205,7 @@ public synchronized FetchResult<T> fetchData(DiscoveryNodes nodes, Set<String> i

// if we are still fetching, return null to indicate it
if (hasAnyNodeFetching(cache)) {
return new FetchResult<>(shardId, null, emptySet());
return new FetchResult<>(null, emptyMap());
} else {
// nothing to fetch, yay, build the return value
Map<DiscoveryNode, T> fetchData = new HashMap<>();
Expand All @@ -177,16 +229,27 @@ public synchronized FetchResult<T> fetchData(DiscoveryNodes nodes, Set<String> i
}
}
}
Set<String> allIgnoreNodes = unmodifiableSet(new HashSet<>(nodesToIgnore));

Map<ShardId, Set<String>> allIgnoreNodesMap = unmodifiableMap(new HashMap<>(shardToIgnoreNodes));
// clear the nodes to ignore, we had a successful run in fetching everything we can
// we need to try them if another full run is needed
nodesToIgnore.clear();
shardToIgnoreNodes.clear();
// if at least one node failed, make sure to have a protective reroute
// here, just case this round won't find anything, and we need to retry fetching data
if (failedNodes.isEmpty() == false || allIgnoreNodes.isEmpty() == false) {
reroute(shardId, "nodes failed [" + failedNodes.size() + "], ignored [" + allIgnoreNodes.size() + "]");

if (failedNodes.isEmpty() == false
|| allIgnoreNodesMap.values().stream().anyMatch(ignoreNodeSet -> ignoreNodeSet.isEmpty() == false)) {
reroute(
reroutingKey,
"nodes failed ["
+ failedNodes.size()
+ "], ignored ["
+ allIgnoreNodesMap.values().stream().mapToInt(Set::size).sum()
+ "]"
);
}
return new FetchResult<>(shardId, fetchData, allIgnoreNodes);

return new FetchResult<>(fetchData, allIgnoreNodesMap);
}
}

Expand All @@ -199,10 +262,10 @@ public synchronized FetchResult<T> fetchData(DiscoveryNodes nodes, Set<String> i
protected synchronized void processAsyncFetch(List<T> responses, List<FailedNodeException> failures, long fetchingRound) {
if (closed) {
// we are closed, no need to process this async fetch at all
logger.trace("{} ignoring fetched [{}] results, already closed", shardId, type);
logger.trace("{} ignoring fetched [{}] results, already closed", reroutingKey, type);
return;
}
logger.trace("{} processing fetched [{}] results", shardId, type);
logger.trace("{} processing fetched [{}] results", reroutingKey, type);

if (responses != null) {
for (T response : responses) {
Expand All @@ -212,7 +275,7 @@ protected synchronized void processAsyncFetch(List<T> responses, List<FailedNode
assert nodeEntry.getFetchingRound() > fetchingRound : "node entries only replaced by newer rounds";
logger.trace(
"{} received response for [{}] from node {} for an older fetching round (expected: {} but was: {})",
shardId,
reroutingKey,
nodeEntry.getNodeId(),
type,
nodeEntry.getFetchingRound(),
Expand All @@ -221,29 +284,29 @@ protected synchronized void processAsyncFetch(List<T> responses, List<FailedNode
} else if (nodeEntry.isFailed()) {
logger.trace(
"{} node {} has failed for [{}] (failure [{}])",
shardId,
reroutingKey,
nodeEntry.getNodeId(),
type,
nodeEntry.getFailure()
);
} else {
// if the entry is there, for the right fetching round and not marked as failed already, process it
logger.trace("{} marking {} as done for [{}], result is [{}]", shardId, nodeEntry.getNodeId(), type, response);
logger.trace("{} marking {} as done for [{}], result is [{}]", reroutingKey, nodeEntry.getNodeId(), type, response);
nodeEntry.doneFetching(response);
}
}
}
}
if (failures != null) {
for (FailedNodeException failure : failures) {
logger.trace("{} processing failure {} for [{}]", shardId, failure, type);
logger.trace("{} processing failure {} for [{}]", reroutingKey, failure, type);
NodeEntry<T> nodeEntry = cache.get(failure.nodeId());
if (nodeEntry != null) {
if (nodeEntry.getFetchingRound() != fetchingRound) {
assert nodeEntry.getFetchingRound() > fetchingRound : "node entries only replaced by newer rounds";
logger.trace(
"{} received failure for [{}] from node {} for an older fetching round (expected: {} but was: {})",
shardId,
reroutingKey,
nodeEntry.getNodeId(),
type,
nodeEntry.getFetchingRound(),
Expand All @@ -261,7 +324,7 @@ protected synchronized void processAsyncFetch(List<T> responses, List<FailedNode
logger.warn(
() -> new ParameterizedMessage(
"{}: failed to list shard for {} on node [{}]",
shardId,
reroutingKey,
type,
failure.nodeId()
),
Expand All @@ -273,13 +336,13 @@ protected synchronized void processAsyncFetch(List<T> responses, List<FailedNode
}
}
}
reroute(shardId, "post_response");
reroute(reroutingKey, "post_response");
}

/**
* Implement this in order to scheduled another round that causes a call to fetch data.
*/
protected abstract void reroute(ShardId shardId, String reason);
protected abstract void reroute(String reroutingKey, String reason);

/**
* Clear cache for node, ensuring next fetch will fetch a fresh copy.
Expand Down Expand Up @@ -334,8 +397,8 @@ private boolean hasAnyNodeFetching(Map<String, NodeEntry<T>> shardCache) {
*/
// visible for testing
void asyncFetch(final DiscoveryNode[] nodes, long fetchingRound) {
logger.trace("{} fetching [{}] from {}", shardId, type, nodes);
action.list(shardId, customDataPath, nodes, new ActionListener<BaseNodesResponse<T>>() {
logger.trace("{} fetching [{}] from {}", reroutingKey, type, nodes);
action.list(shardAttributesMap, nodes, new ActionListener<BaseNodesResponse<T>>() {
@Override
public void onResponse(BaseNodesResponse<T> response) {
processAsyncFetch(response.getNodes(), response.failures(), fetchingRound);
Expand All @@ -358,14 +421,12 @@ public void onFailure(Exception e) {
*/
public static class FetchResult<T extends BaseNodeResponse> {

private final ShardId shardId;
private final Map<DiscoveryNode, T> data;
private final Set<String> ignoreNodes;
private final Map<ShardId, Set<String>> ignoredShardToNodes;

public FetchResult(ShardId shardId, Map<DiscoveryNode, T> data, Set<String> ignoreNodes) {
this.shardId = shardId;
public FetchResult(Map<DiscoveryNode, T> data, Map<ShardId, Set<String>> ignoreNodes) {
this.data = data;
this.ignoreNodes = ignoreNodes;
this.ignoredShardToNodes = ignoreNodes;
}

/**
Expand All @@ -389,9 +450,14 @@ public Map<DiscoveryNode, T> getData() {
* Process any changes needed to the allocation based on this fetch result.
*/
public void processAllocation(RoutingAllocation allocation) {
for (String ignoreNode : ignoreNodes) {
allocation.addIgnoreShardForNode(shardId, ignoreNode);
for (Map.Entry<ShardId, Set<String>> entry : ignoredShardToNodes.entrySet()) {
ShardId shardId = entry.getKey();
Set<String> ignoreNodes = entry.getValue();
if (ignoreNodes.isEmpty() == false) {
ignoreNodes.forEach(nodeId -> allocation.addIgnoreShardForNode(shardId, nodeId));
}
}

}
}

Expand Down
11 changes: 10 additions & 1 deletion server/src/main/java/org/opensearch/gateway/TransportNodesListGatewayStartedShards.java
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Original file line number Diff line number Diff line change
Expand Up @@ -62,12 +62,14 @@
import org.opensearch.index.store.Store;
import org.opensearch.indices.IndicesService;
import org.opensearch.indices.replication.checkpoint.ReplicationCheckpoint;
import org.opensearch.indices.store.ShardAttributes;
import org.opensearch.threadpool.ThreadPool;
import org.opensearch.transport.TransportRequest;
import org.opensearch.transport.TransportService;

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
Expand Down Expand Up @@ -124,7 +126,14 @@ public TransportNodesListGatewayStartedShards(
}

@Override
public void list(ShardId shardId, String customDataPath, DiscoveryNode[] nodes, ActionListener<NodesGatewayStartedShards> listener) {
public void list(
Map<ShardId, ShardAttributes> shardAttributesMap,
DiscoveryNode[] nodes,
ActionListener<NodesGatewayStartedShards> listener
) {
assert shardAttributesMap.size() == 1 : "only one shard should be specified";
final ShardId shardId = shardAttributesMap.keySet().iterator().next();
final String customDataPath = shardAttributesMap.get(shardId).getCustomDataPath();
execute(new Request(shardId, customDataPath, nodes), listener);
}

Expand Down
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