{"record":{"id":"caa54357883aa9a2","repo":"vitessio/vitess","slug":"reloadschemas-failed-to-acquire-toporeadpool-w","errorCode":null,"errorMessage":"ReloadSchemas: failed to acquire topoReadPool: %w","messagePattern":"ReloadSchemas: failed to acquire topoReadPool: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"go/vt/vtadmin/cluster/cluster.go","lineNumber":2197,"sourceCode":"\t\tresp.KeyspaceResults, err = c.reloadKeyspaceSchemas(ctx, req)\n\t}\n\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\n\treturn &resp, nil\n}\n\n// reloadKeyspaceSchemas reloads schemas in one or more keyspaces in the\n// cluster.\nfunc (c *Cluster) reloadKeyspaceSchemas(ctx context.Context, req *vtadminpb.ReloadSchemasRequest) ([]*vtadminpb.ReloadSchemasResponse_KeyspaceResult, error) {\n\tkeyspaces, err := func() (keyspaces []*vtctldatapb.Keyspace, err error) {\n\t\tspan, ctx := trace.NewSpan(ctx, \"Cluster.GetKeyspaces\")\n\t\tdefer span.Finish()\n\n\t\tif err := c.topoReadPool.Acquire(ctx); err != nil {\n\t\t\treturn nil, fmt.Errorf(\"ReloadSchemas: failed to acquire topoReadPool: %w\", err)\n\t\t}\n\n\t\t// Load all keyspaces up front so we don't have to make one-trip per\n\t\t// keyspace to check its existence.\n\t\tresp, err := c.Vtctld.GetKeyspaces(ctx, &vtctldatapb.GetKeyspacesRequest{})\n\t\tif err != nil {\n\t\t\treturn nil, err\n\t\t}\n\n\t\t// The request specified no keyspace names, so default to all of them.\n\t\tif len(req.Keyspaces) == 0 {\n\t\t\treturn resp.Keyspaces, nil\n\t\t}\n\n\t\tkeyspaceNames := sets.New[string](req.Keyspaces...)\n\n\t\tfor _, ks := range resp.Keyspaces {\n\t\t\tif keyspaceNames.Has(ks.Name) {","sourceCodeStart":2179,"sourceCodeEnd":2215,"githubUrl":"https://github.com/vitessio/vitess/blob/01a25a7d176f94613b8d59d799f438380a8760e4/go/vt/vtadmin/cluster/cluster.go#L2179-L2215","documentation":"reloadKeyspaceSchemas (used by Cluster.ReloadSchemas) first acquires topoReadPool to list all keyspaces in one pass. If Acquire fails due to context cancellation or pool exhaustion, the error is wrapped as 'ReloadSchemas: failed to acquire topoReadPool'.","triggerScenarios":"Calling ReloadSchemas while topoReadPool is saturated (other topo reads in flight) or the request context is cancelled before the keyspace listing begins.","commonSituations":"Cluster-wide schema reload triggered while dashboards/other calls are doing topo reads; broad schema reload across many keyspaces combined with slow topo backend; upstream HTTP request deadline already expired.","solutions":["Retry ReloadSchemas with a fresh, longer-lived context","Reduce concurrent topo read load (stagger schema reload requests)","Increase topo_read_pool_size in vtadmin config","Check topo backend latency/health"],"exampleFix":"// before\nctx, cancel := context.WithTimeout(context.Background(), time.Second)\n_, err := c.ReloadSchemas(ctx, req)\n// after\nctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)\n_, err := c.ReloadSchemas(ctx, req)","handlingStrategy":"retry","validationCode":"if ctx.Err() != nil {\n    return ctx.Err()\n}","typeGuard":null,"tryCatchPattern":"res, err := c.ReloadSchemas(ctx, req)\nif err != nil && strings.Contains(err.Error(), \"failed to acquire topoReadPool\") {\n    // back off and retry with a longer-lived context\n}","preventionTips":["Schedule schema reloads away from topo-heavy operations","Use long-enough request deadlines for cluster-wide reloads","Stagger reload requests across clients"],"tags":["vtadmin","concurrency","topo","schema-reload"],"backgroundTag":"semaphore-acquisition-failed","analyzedSha":"01a25a7d176f94613b8d59d799f438380a8760e4","analyzedAt":"2026-09-01T17:28:30.605Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}