added links and fixed docs

Author: ardan-bkennedy

Opening.md

@@ -17,4 +17,4 @@ Slack:    [Slack](https://invite.slack.golangbridge.org)
 Graphviz: https://www.graphviz.org/  
 go get -u github.com/rakyll/hey   : Or use ab  
 go get -u github.com/ardanlabs/gotraining  
-Latest Version of Go: 1.11  
+Latest Version of Go: 1.12   

reading/README.md

@@ -111,13 +111,28 @@ There is a ton of links to extra reading and videos through out the material. Oc
 [Go’s hidden #pragmas](https://dave.cheney.net/2018/01/08/gos-hidden-pragmas) - Dave Cheney  
 [Post-mortem debugging of Go Programs](https://fntlnz.wtf/post/gopostmortem/) - Lorenzo Fontana   
 [A Crash Course in Modern Hardware](https://www.youtube.com/watch?v=OFgxAFdxYAQ) - Cliff Click  
+[How I investigated memory leaks in Go using pprof on a large codebase](https://medium.freecodecamp.org/how-i-investigated-memory-leaks-in-go-using-pprof-on-a-large-codebase-4bec4325e192) - Jonathan Levison   
 
 ### API Design
 
 [You wanted a banana but you got a gorilla holding the banana](http://www.johndcook.com/blog/2011/07/19/you-wanted-banana) - John D. Cook  
 [Focus On Being Precise](https://www.ardanlabs.com/blog/2018/02/focus-on-being-precise.html) - William Kennedy  
 [Design, Composition and Performance](https://www.infoq.com/presentations/Design-Composition-Performance) - Rich Hickey  
 
+### Error Handling
+
+[Go 1.13: xerrors](https://crawshaw.io/blog/xerrors) - David Crawshaw  
+[Error handling and Go](https://blog.golang.org/error-handling-and-go)    
+[Error Handling In Go, Part I](https://www.ardanlabs.com/blog/2014/10/error-handling-in-go-part-i.html) - William Kennedy    
+[Error Handling In Go, Part II](https://www.ardanlabs.com/blog/2014/11/error-handling-in-go-part-ii.html) - William Kennedy    
+[Design Philosophy On Logging](https://www.ardanlabs.com/blog/2017/05/design-philosophy-on-logging.html) - William Kennedy    
+[Bugs are a failure of prediction](https://clipperhouse.com/bugs-are-a-failure-of-prediction/) - Matt Sherman    
+[Inspecting errors](https://dave.cheney.net/2014/12/24/inspecting-errors) - Dave Cheney    
+[Don’t just check errors, handle them gracefully](https://dave.cheney.net/2016/04/27/dont-just-check-errors-handle-them-gracefully) - Dave Cheney    
+[Stack traces and the errors package](https://dave.cheney.net/2016/06/12/stack-traces-and-the-errors-package) - Dave Cheney    
+[Errors are handled in return values](https://plus.google.com/+RussCox-rsc/posts/iqAiKAwP6Ce) - Russ Cox    
+[Error handling in Upspin](https://commandcenter.blogspot.com/2017/12/error-handling-in-upspin.html) - Rob Pike    
+
 ### Interfaces and Composition
 
 [Repeat yourself, do more than one thing, and rewrite everything](https://programmingisterrible.com/post/176657481103/repeat-yourself-do-more-than-one-thing-and) - tef  

topics/go/design/error_handling/README.md

@@ -25,6 +25,7 @@ _Systems cannot be developed assuming that human beings will be able to write mi
 [Stack traces and the errors package](https://dave.cheney.net/2016/06/12/stack-traces-and-the-errors-package) - Dave Cheney    
 [Errors are handled in return values](https://plus.google.com/+RussCox-rsc/posts/iqAiKAwP6Ce) - Russ Cox    
 [Error handling in Upspin](https://commandcenter.blogspot.com/2017/12/error-handling-in-upspin.html) - Rob Pike    
+[Go 1.13: xerrors](https://crawshaw.io/blog/xerrors) - David Crawshaw  
 
 ## Code Review
 

topics/go/profiling/trace/trace.go

@@ -41,8 +41,8 @@ func main() {
 	// pprof.StartCPUProfile(os.Stdout)
 	// defer pprof.StopCPUProfile()
 
-	// trace.Start(os.Stdout)
-	// defer trace.Stop()
+	trace.Start(os.Stdout)
+	defer trace.Stop()
 
 	docs := make([]string, 4000)
 	for i := range docs {
@@ -62,43 +62,65 @@ func main() {
 }
 
 func find(topic string, docs []string) int {
-	var found int
+	var found int32
 
-	for _, doc := range docs {
-		file := fmt.Sprintf("%s.xml", doc[:8])
-		f, err := os.OpenFile(file, os.O_RDONLY, 0)
-		if err != nil {
-			log.Printf("Opening Document [%s] : ERROR : %v", doc, err)
-			return 0
-		}
+	g := runtime.NumCPU()
+	var wg sync.WaitGroup
+	wg.Add(g)
 
-		data, err := ioutil.ReadAll(f)
-		if err != nil {
-			f.Close()
-			log.Printf("Reading Document [%s] : ERROR : %v", doc, err)
-			return 0
-		}
-		f.Close()
+	ch := make(chan string, g)
 
-		var d document
-		if err := xml.Unmarshal(data, &d); err != nil {
-			log.Printf("Decoding Document [%s] : ERROR : %v", doc, err)
-			return 0
-		}
+	for i := 0; i < g; i++ {
+		go func() {
+			var lFound int32
+			defer func() {
+				atomic.AddInt32(&found, lFound)
+				wg.Done()
+			}()
 
-		for _, item := range d.Channel.Items {
-			if strings.Contains(item.Title, topic) {
-				found++
-				continue
-			}
+			for doc := range ch {
+				file := fmt.Sprintf("%s.xml", doc[:8])
+				f, err := os.OpenFile(file, os.O_RDONLY, 0)
+				if err != nil {
+					log.Printf("Opening Document [%s] : ERROR : %v", doc, err)
+					return
+				}
+
+				data, err := ioutil.ReadAll(f)
+				if err != nil {
+					f.Close()
+					log.Printf("Reading Document [%s] : ERROR : %v", doc, err)
+					return
+				}
+				f.Close()
+
+				var d document
+				if err := xml.Unmarshal(data, &d); err != nil {
+					log.Printf("Decoding Document [%s] : ERROR : %v", doc, err)
+					return
+				}
+
+				for _, item := range d.Channel.Items {
+					if strings.Contains(item.Title, topic) {
+						lFound++
+						continue
+					}
 
-			if strings.Contains(item.Description, topic) {
-				found++
+					if strings.Contains(item.Description, topic) {
+						lFound++
+					}
+				}
 			}
-		}
+		}()
 	}
 
-	return found
+	for _, doc := range docs {
+		ch <- doc
+	}
+	close(ch)
+
+	wg.Wait()
+	return int(found)
 }
 
 func findConcurrent(topic string, docs []string) int {