[
https://issues.apache.org/jira/browse/BEAM-4852?focusedWorklogId=129536&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-129536
]
ASF GitHub Bot logged work on BEAM-4852:
----------------------------------------
Author: ASF GitHub Bot
Created on: 31/Jul/18 23:40
Start Date: 31/Jul/18 23:40
Worklog Time Spent: 10m
Work Description: herohde closed pull request #6052: [BEAM-4852] Only
read symbol table when required.
URL: https://github.com/apache/beam/pull/6052
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git a/sdks/go/pkg/beam/core/runtime/symbols.go
b/sdks/go/pkg/beam/core/runtime/symbols.go
index 238823696a8..c4f68163393 100644
--- a/sdks/go/pkg/beam/core/runtime/symbols.go
+++ b/sdks/go/pkg/beam/core/runtime/symbols.go
@@ -26,23 +26,41 @@ import (
)
var (
+ // Resolver is the accessible symbol resolver the runtime uses to find
functions.
Resolver SymbolResolver
cache = make(map[string]interface{})
mu sync.Mutex
)
func init() {
+ // defer initialization of the default resolver. This way
+ // the symbol table isn't read in unless strictly necessary.
+ Resolver = &deferedResolver{initFn: initResolver}
+}
+
+type deferedResolver struct {
+ initFn func() SymbolResolver
+ r SymbolResolver
+ init sync.Once
+}
+
+func (d *deferedResolver) Sym2Addr(name string) (uintptr, error) {
+ d.init.Do(func() {
+ d.r = d.initFn()
+ })
+ return d.r.Sym2Addr(name)
+}
+
+func initResolver() SymbolResolver {
// First try the Linux location, since it's the most reliable.
if r, err := symtab.New("/proc/self/exe"); err == nil {
- Resolver = r
- return
+ return r
}
// For other OS's this works in most cases we need.
if r, err := symtab.New(os.Args[0]); err == nil {
- Resolver = r
- return
+ return r
}
- Resolver = failResolver(false)
+ return failResolver(false)
}
// SymbolResolver resolves a symbol to an unsafe address.
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Issue Time Tracking
-------------------
Worklog Id: (was: 129536)
Time Spent: 1h 20m (was: 1h 10m)
> [Go SDK] Beam should not retain the symbol table after function resolution
> --------------------------------------------------------------------------
>
> Key: BEAM-4852
> URL: https://issues.apache.org/jira/browse/BEAM-4852
> Project: Beam
> Issue Type: Improvement
> Components: sdk-go
> Reporter: Robert Burke
> Assignee: Robert Burke
> Priority: Major
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> In some instances, Beam Go requires introspecting the symbol table for the
> binary to resolve functions. However it may be possible to cache these
> results for all applicable functions, and then allow the table to be garbage
> collected.
> The table represents a large heap cost that is retained for the lifetime of a
> job.
> A secondary goal would be to avoid incurring the cost entirely when there's
> nothing to look up for a job. Eg for unit tests, or ancillary uses of the
> beam SDK (eg. migrating from some other system to beam shouldn't incur the
> cost when the old system is being used, just because beam is linked in and
> triggered by a runtime switch).
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