go122-create-syscall-with-p.go

Documentation: internal/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  // Tests a G being created from within a syscall.
     6  //
     7  // Specifically, it tests a scenario wherein a C
     8  // thread is calling into Go, creating a goroutine in
     9  // a syscall (in the tracer's model). Because the actual
    10  // m can be reused, it's possible for that m to have never
    11  // had its P (in _Psyscall) stolen if the runtime doesn't
    12  // model the scenario correctly. Make sure we reject such
    13  // traces.
    14  
    15  package main
    16  
    17  import (
    18  	"internal/trace"
    19  	"internal/trace/internal/testgen"
    20  	"internal/trace/tracev2"
    21  	"internal/trace/version"
    22  )
    23  
    24  func main() {
    25  	testgen.Main(version.Go122, gen)
    26  }
    27  
    28  func gen(t *testgen.Trace) {
    29  	t.ExpectFailure(".*expected a proc but didn't have one.*")
    30  
    31  	g := t.Generation(1)
    32  
    33  	// A C thread calls into Go and acquires a P. It returns
    34  	// back to C, destroying the G. It then comes back to Go
    35  	// on the same thread and again returns to C.
    36  	//
    37  	// Note: on pthread platforms this can't happen on the
    38  	// same thread because the m is stashed in TLS between
    39  	// calls into Go, until the thread dies. This is still
    40  	// possible on other platforms, however.
    41  	b0 := g.Batch(trace.ThreadID(0), 0)
    42  	b0.Event("GoCreateSyscall", trace.GoID(4))
    43  	b0.Event("ProcStatus", trace.ProcID(0), tracev2.ProcIdle)
    44  	b0.Event("ProcStart", trace.ProcID(0), testgen.Seq(1))
    45  	b0.Event("GoSyscallEndBlocked")
    46  	b0.Event("GoStart", trace.GoID(4), testgen.Seq(1))
    47  	b0.Event("GoSyscallBegin", testgen.Seq(2), testgen.NoStack)
    48  	b0.Event("GoDestroySyscall")
    49  	b0.Event("GoCreateSyscall", trace.GoID(4))
    50  	b0.Event("GoSyscallEnd")
    51  	b0.Event("GoSyscallBegin", testgen.Seq(3), testgen.NoStack)
    52  	b0.Event("GoDestroySyscall")
    53  }
    54
View as plain text