go122-create-syscall-with-p.go

Documentation: golang.org/x/exp/trace/testdata/generators

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Code generated by "gen.bash" from internal/trace/v2; DO NOT EDIT.
     6  
     7  //go:build go1.21
     8  
     9  // Tests a G being created from within a syscall.
    10  //
    11  // Specifically, it tests a scenerio wherein a C
    12  // thread is calling into Go, creating a goroutine in
    13  // a syscall (in the tracer's model). Because the actual
    14  // m can be reused, it's possible for that m to have never
    15  // had its P (in _Psyscall) stolen if the runtime doesn't
    16  // model the scenario correctly. Make sure we reject such
    17  // traces.
    18  
    19  package main
    20  
    21  import (
    22  	"golang.org/x/exp/trace"
    23  	"golang.org/x/exp/trace/internal/event/go122"
    24  	testgen "golang.org/x/exp/trace/internal/testgen/go122"
    25  )
    26  
    27  func main() {
    28  	testgen.Main(gen)
    29  }
    30  
    31  func gen(t *testgen.Trace) {
    32  	t.ExpectFailure(".*expected a proc but didn't have one.*")
    33  
    34  	g := t.Generation(1)
    35  
    36  	// A C thread calls into Go and acquires a P. It returns
    37  	// back to C, destroying the G. It then comes back to Go
    38  	// on the same thread and again returns to C.
    39  	//
    40  	// Note: on pthread platforms this can't happen on the
    41  	// same thread because the m is stashed in TLS between
    42  	// calls into Go, until the thread dies. This is still
    43  	// possible on other platforms, however.
    44  	b0 := g.Batch(trace.ThreadID(0), 0)
    45  	b0.Event("GoCreateSyscall", trace.GoID(4))
    46  	b0.Event("ProcStatus", trace.ProcID(0), go122.ProcIdle)
    47  	b0.Event("ProcStart", trace.ProcID(0), testgen.Seq(1))
    48  	b0.Event("GoSyscallEndBlocked")
    49  	b0.Event("GoStart", trace.GoID(4), testgen.Seq(1))
    50  	b0.Event("GoSyscallBegin", testgen.Seq(2), testgen.NoStack)
    51  	b0.Event("GoDestroySyscall")
    52  	b0.Event("GoCreateSyscall", trace.GoID(4))
    53  	b0.Event("GoSyscallEnd")
    54  	b0.Event("GoSyscallBegin", testgen.Seq(3), testgen.NoStack)
    55  	b0.Event("GoDestroySyscall")
    56  }
    57
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