add query cancel sync for presto forward #41
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ethanyzhang
requested changes
Feb 11, 2025
| queryStateFailed = "FAILED" | ||
| ) | ||
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| type QueryCache struct { |
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Suggested change
| type QueryCache struct { | |
| type QueryCacheEntry struct { |
to be more precise
| runningTasks sync.WaitGroup | ||
| failedToForward atomic.Uint32 | ||
| forwarded atomic.Uint32 | ||
| runningQueriesCacheMap = make(map[string]*[]QueryCache) |
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Please add a comment for this, what is the kay and value for.
| @@ -171,6 +187,16 @@ func Run(_ *cobra.Command, _ []string) { | |||
| Msgf("finished forwarding queries") | |||
| } | |||
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| func checkAndCancelQuery(ctx context.Context, queryState *presto.QueryStateInfo) { | |||
| if queryCaches, ok := runningQueriesCacheMap[queryState.QueryId]; ok { | |||
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| if queryCaches, ok := runningQueriesCacheMap[queryState.QueryId]; ok { | |
| if queryCacheEntries, ok := runningQueriesCacheMap[queryState.QueryId]; ok { |
| @@ -226,9 +252,10 @@ func forwardQuery(ctx context.Context, queryState *presto.QueryStateInfo, client | |||
| } | |||
| successful, failed := atomic.Uint32{}, atomic.Uint32{} | |||
| forwardedQueries := sync.WaitGroup{} | |||
| cachedQueries := []QueryCache{} | |||
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| cachedQueries := []QueryCache{} | |
| cachedQueries := make([]QueryCache, len(clients)-1) |
Pre-allocate the elements to prevent racing conditions.
See my comment below.
| ) | ||
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| type QueryCache struct { | ||
| QueryId string |
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seems like we do not need the QueryId field here right?
| @@ -246,6 +273,10 @@ func forwardQuery(ctx context.Context, queryState *presto.QueryStateInfo, client | |||
| failed.Add(1) | |||
| return | |||
| } | |||
| //build cache for running query | |||
| if clientResult.NextUri != nil { | |||
| *cachedQueries = append(*cachedQueries, QueryCache{QueryId: clientResult.Id, NextUri: *clientResult.NextUri, Client: client}) | |||
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Here you write to cachedQueries concurrently, which could lead to issues.
In the comment above I requested to pre-allocate the elements. so here you can just update element using index i-1, without needing to update the cachedQueries value
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Background:
Presto forward is a feature to monitor the workload in source Presto cluster and then clone the workload to target clusters.
It's well working. There is one requirement which to syncronize the query cancel to target clusters. That means when the workload is canceled in source cluster, the target cluster should cancel the workload as well.
Solution: