*: tidb tracing prototype #7016
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| // Copyright 2018 PingCAP, Inc. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package executor | ||
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| import ( | ||
| "fmt" | ||
| "time" | ||
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| "github.com/juju/errors" | ||
| "github.com/opentracing/basictracer-go" | ||
| opentracing "github.com/opentracing/opentracing-go" | ||
| "github.com/pingcap/tidb/plan" | ||
| "github.com/pingcap/tidb/util/chunk" | ||
| "github.com/pingcap/tidb/util/tracing" | ||
| "golang.org/x/net/context" | ||
| ) | ||
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| // TraceExec represents a root executor of trace query. | ||
| type TraceExec struct { | ||
| baseExecutor | ||
| // CollectedSpans collects all span during execution. Span is appended via | ||
| // callback method which passes into tracer implementation. | ||
| CollectedSpans []basictracer.RawSpan | ||
| // exhausted being true means there is no more result. | ||
| exhausted bool | ||
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| // plan is the real query plan and it is used for building real query's executor. | ||
| plan plan.Plan | ||
| // rootTrace represents root span which is father of all other span. | ||
| rootTrace opentracing.Span | ||
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| childrenResults []*chunk.Chunk | ||
| } | ||
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| // buildTrace builds a TraceExec for future executing. This method will be called | ||
| // at build(). | ||
| func (b *executorBuilder) buildTrace(v *plan.Trace) Executor { | ||
|
There was a problem hiding this comment. It's better to maintain this function in the "builder.go" file, like other functions. |
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| e := &TraceExec{ | ||
| baseExecutor: newBaseExecutor(b.ctx, v.Schema(), v.ExplainID()), | ||
| } | ||
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| pp, _ := v.StmtPlan.(plan.PhysicalPlan) | ||
| e.children = make([]Executor, 0, len(pp.Children())) | ||
| for _, child := range pp.Children() { | ||
| switch p := child.(type) { | ||
| case *plan.PhysicalTableReader, *plan.PhysicalIndexReader, *plan.PhysicalIndexLookUpReader, *plan.PhysicalHashAgg, *plan.PhysicalProjection, *plan.PhysicalStreamAgg, *plan.PhysicalSort: | ||
|
There was a problem hiding this comment. please split the long code line. There was a problem hiding this comment. seems these operators are also not supported in this PR? |
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| e.children = append(e.children, b.build(p)) | ||
| default: | ||
| panic(fmt.Sprintf("%v is not supported", child)) | ||
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There was a problem hiding this comment. Do not panic, set |
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| } | ||
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| } | ||
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| return e | ||
| } | ||
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| // Open opens a trace executor and it will create a root trace span which will be | ||
| // used for the following span in a relationship of `ChildOf` or `FollowFrom`. | ||
| // for more details, you could refer to http://opentracing.io | ||
| func (e *TraceExec) Open(ctx context.Context) error { | ||
|
There was a problem hiding this comment. seems that we can not trace the building and optimization time of a query, only the execution time can be traced? There was a problem hiding this comment. It is only for now. I will file another PR to support this. There was a problem hiding this comment. Since the |
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| e.rootTrace = tracing.NewRecordedTrace("trace_exec", func(sp basictracer.RawSpan) { | ||
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There was a problem hiding this comment. After that, global opentracing Tracer is modified? There was a problem hiding this comment. Yes. I will file another PR to better handle this. |
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| e.CollectedSpans = append(e.CollectedSpans, sp) | ||
| }) | ||
| // we actually don't care when underlying executor started. We only care how | ||
| // much time was spent | ||
| for _, child := range e.children { | ||
|
There was a problem hiding this comment. only need to call |
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| err := child.Open(ctx) | ||
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There was a problem hiding this comment. Will some node open multiple times? There was a problem hiding this comment. Usually, it is not. I just copied the code from basicExecutor with some addition about how to set up tracing. |
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| if err != nil { | ||
| return errors.Trace(err) | ||
| } | ||
| } | ||
| e.childrenResults = make([]*chunk.Chunk, 0, len(e.children)) | ||
|
There was a problem hiding this comment. only one |
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| for _, child := range e.children { | ||
| e.childrenResults = append(e.childrenResults, child.newChunk()) | ||
| } | ||
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| return nil | ||
| } | ||
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| // Next executes real query and collects span later. | ||
| func (e *TraceExec) Next(ctx context.Context, chk *chunk.Chunk) error { | ||
| chk.Reset() | ||
| if e.exhausted { | ||
| return nil | ||
| } | ||
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| // store span into context | ||
| ctx = opentracing.ContextWithSpan(ctx, e.rootTrace) | ||
| if len(e.children) > 0 { | ||
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| for { | ||
| if err := e.children[0].Next(ctx, e.childrenResults[0]); err != nil { | ||
| return errors.Trace(err) | ||
| } | ||
| if e.childrenResults[0].NumRows() != 0 { | ||
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There was a problem hiding this comment.
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| break | ||
| } | ||
| } | ||
| } | ||
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| e.rootTrace.LogKV("event", "tracing completed") | ||
| e.rootTrace.Finish() | ||
| var rootSpan basictracer.RawSpan | ||
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| treeSpans := make(map[uint64][]basictracer.RawSpan) | ||
| for _, sp := range e.CollectedSpans { | ||
| treeSpans[sp.ParentSpanID] = append(treeSpans[sp.ParentSpanID], sp) | ||
| // if a span's parentSpanID is 0, then it is root span | ||
| // this is by design | ||
| if sp.ParentSpanID == 0 { | ||
| rootSpan = sp | ||
| } | ||
| } | ||
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| dfsTree(rootSpan, treeSpans, "", false, chk) | ||
| e.exhausted = true | ||
| return nil | ||
| } | ||
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| func dfsTree(span basictracer.RawSpan, tree map[uint64][]basictracer.RawSpan, prefix string, isLast bool, chk *chunk.Chunk) { | ||
| suffix := "" | ||
| spans := tree[span.Context.SpanID] | ||
| var newPrefix string | ||
| if span.ParentSpanID == 0 { | ||
| newPrefix = prefix | ||
| } else { | ||
| if len(tree[span.ParentSpanID]) > 0 && !isLast { | ||
| suffix = "├─" | ||
| newPrefix = prefix + "│ " | ||
| } else { | ||
| suffix = "└─" | ||
| newPrefix = prefix + " " | ||
| } | ||
| } | ||
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| chk.AppendString(0, prefix+suffix+span.Operation) | ||
| chk.AppendString(1, span.Start.Format(time.StampNano)) | ||
| chk.AppendString(2, span.Duration.String()) | ||
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| for i, sp := range spans { | ||
| dfsTree(sp, tree, newPrefix, i == (len(spans))-1 /*last element of array*/, chk) | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| package plan | ||
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| import ( | ||
| "github.com/juju/errors" | ||
| "github.com/pingcap/tidb/ast" | ||
| "github.com/pingcap/tidb/expression" | ||
| "github.com/pingcap/tidb/mysql" | ||
| ) | ||
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| // Trace represents a trace plan. | ||
| type Trace struct { | ||
| baseSchemaProducer | ||
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| StmtPlan Plan | ||
| } | ||
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| // buildTrace builds a trace plan. Inside this method, it first optimize the | ||
| // underlying query and then constructs a schema, which will be used to constructs | ||
| // rows result. | ||
| func (b *planBuilder) buildTrace(trace *ast.TraceStmt) (Plan, error) { | ||
| if _, ok := trace.Stmt.(*ast.SelectStmt); !ok { | ||
| return nil, errors.New("trace only supports select query") | ||
|
There was a problem hiding this comment. how about "only the select statement can be traced"? |
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| } | ||
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| optimizedP, err := Optimize(b.ctx, trace.Stmt, b.is) | ||
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| if err != nil { | ||
| return nil, errors.New("fail to optimize during build trace") | ||
|
There was a problem hiding this comment. Why not return the error directly? There was a problem hiding this comment. creating a new error with error message |
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| } | ||
| p := &Trace{StmtPlan: optimizedP} | ||
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| retFields := []string{"operation", "duration", "spanID"} | ||
| schema := expression.NewSchema(make([]*expression.Column, 0, len(retFields))...) | ||
| schema.Append(buildColumn("", "operation", mysql.TypeString, mysql.MaxBlobWidth)) | ||
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| schema.Append(buildColumn("", "startTS", mysql.TypeString, mysql.MaxBlobWidth)) | ||
| schema.Append(buildColumn("", "duration", mysql.TypeString, mysql.MaxBlobWidth)) | ||
| p.SetSchema(schema) | ||
| return p, nil | ||
| } | ||
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why remove this?