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diff --git a/doc/go1.3.html b/doc/go1.3.html deleted file mode 100644 index 18b3ec65d2..0000000000 --- a/doc/go1.3.html +++ /dev/null @@ -1,608 +0,0 @@ -<!--{ - "Title": "Go 1.3 Release Notes", - "Path": "/doc/go1.3", - "Template": true -}--> - -<h2 id="introduction">Introduction to Go 1.3</h2> - -<p> -The latest Go release, version 1.3, arrives six months after 1.2, -and contains no language changes. -It focuses primarily on implementation work, providing -precise garbage collection, -a major refactoring of the compiler toolchain that results in -faster builds, especially for large projects, -significant performance improvements across the board, -and support for DragonFly BSD, Solaris, Plan 9 and Google's Native Client architecture (NaCl). -It also has an important refinement to the memory model regarding synchronization. -As always, Go 1.3 keeps the <a href="/doc/go1compat.html">promise -of compatibility</a>, -and almost everything -will continue to compile and run without change when moved to 1.3. -</p> - -<h2 id="os">Changes to the supported operating systems and architectures</h2> - -<h3 id="win2000">Removal of support for Windows 2000</h3> - -<p> -Microsoft stopped supporting Windows 2000 in 2010. -Since it has <a href="https://codereview.appspot.com/74790043">implementation difficulties</a> -regarding exception handling (signals in Unix terminology), -as of Go 1.3 it is not supported by Go either. -</p> - -<h3 id="dragonfly">Support for DragonFly BSD</h3> - -<p> -Go 1.3 now includes experimental support for DragonFly BSD on the <code>amd64</code> (64-bit x86) and <code>386</code> (32-bit x86) architectures. -It uses DragonFly BSD 3.6 or above. -</p> - -<h3 id="freebsd">Support for FreeBSD</h3> - -<p> -It was not announced at the time, but since the release of Go 1.2, support for Go on FreeBSD -requires FreeBSD 8 or above. -</p> - -<p> -As of Go 1.3, support for Go on FreeBSD requires that the kernel be compiled with the -<code>COMPAT_FREEBSD32</code> flag configured. -</p> - -<p> -In concert with the switch to EABI syscalls for ARM platforms, Go 1.3 will run only on FreeBSD 10. -The x86 platforms, 386 and amd64, are unaffected. -</p> - -<h3 id="nacl">Support for Native Client</h3> - -<p> -Support for the Native Client virtual machine architecture has returned to Go with the 1.3 release. -It runs on the 32-bit Intel architectures (<code>GOARCH=386</code>) and also on 64-bit Intel, but using -32-bit pointers (<code>GOARCH=amd64p32</code>). -There is not yet support for Native Client on ARM. -Note that this is Native Client (NaCl), not Portable Native Client (PNaCl). -Details about Native Client are <a href="https://developers.google.com/native-client/dev/">here</a>; -how to set up the Go version is described <a href="//golang.org/wiki/NativeClient">here</a>. -</p> - -<h3 id="netbsd">Support for NetBSD</h3> - -<p> -As of Go 1.3, support for Go on NetBSD requires NetBSD 6.0 or above. -</p> - -<h3 id="openbsd">Support for OpenBSD</h3> - -<p> -As of Go 1.3, support for Go on OpenBSD requires OpenBSD 5.5 or above. -</p> - -<h3 id="plan9">Support for Plan 9</h3> - -<p> -Go 1.3 now includes experimental support for Plan 9 on the <code>386</code> (32-bit x86) architecture. -It requires the <code>Tsemacquire</code> syscall, which has been in Plan 9 since June, 2012. -</p> - -<h3 id="solaris">Support for Solaris</h3> - -<p> -Go 1.3 now includes experimental support for Solaris on the <code>amd64</code> (64-bit x86) architecture. -It requires illumos, Solaris 11 or above. -</p> - -<h2 id="memory">Changes to the memory model</h2> - -<p> -The Go 1.3 memory model <a href="https://codereview.appspot.com/75130045">adds a new rule</a> -concerning sending and receiving on buffered channels, -to make explicit that a buffered channel can be used as a simple -semaphore, using a send into the -channel to acquire and a receive from the channel to release. -This is not a language change, just a clarification about an expected property of communication. -</p> - -<h2 id="impl">Changes to the implementations and tools</h2> - -<h3 id="stacks">Stack</h3> - -<p> -Go 1.3 has changed the implementation of goroutine stacks away from the old, -"segmented" model to a contiguous model. -When a goroutine needs more stack -than is available, its stack is transferred to a larger single block of memory. -The overhead of this transfer operation amortizes well and eliminates the old "hot spot" -problem when a calculation repeatedly steps across a segment boundary. -Details including performance numbers are in this -<a href="//golang.org/s/contigstacks">design document</a>. -</p> - -<h3 id="garbage_collector">Changes to the garbage collector</h3> - -<p> -For a while now, the garbage collector has been <em>precise</em> when examining -values in the heap; the Go 1.3 release adds equivalent precision to values on the stack. -This means that a non-pointer Go value such as an integer will never be mistaken for a -pointer and prevent unused memory from being reclaimed. -</p> - -<p> -Starting with Go 1.3, the runtime assumes that values with pointer type -contain pointers and other values do not. -This assumption is fundamental to the precise behavior of both stack expansion -and garbage collection. -Programs that use <a href="/pkg/unsafe/">package unsafe</a> -to store integers in pointer-typed values are illegal and will crash if the runtime detects the behavior. -Programs that use <a href="/pkg/unsafe/">package unsafe</a> to store pointers -in integer-typed values are also illegal but more difficult to diagnose during execution. -Because the pointers are hidden from the runtime, a stack expansion or garbage collection -may reclaim the memory they point at, creating -<a href="//en.wikipedia.org/wiki/Dangling_pointer">dangling pointers</a>. -</p> - -<p> -<em>Updating</em>: Code that uses <code>unsafe.Pointer</code> to convert -an integer-typed value held in memory into a pointer is illegal and must be rewritten. -Such code can be identified by <code>go vet</code>. -</p> - -<h3 id="map">Map iteration</h3> - -<p> -Iterations over small maps no longer happen in a consistent order. -Go 1 defines that “<a href="//golang.org/ref/spec#For_statements">The iteration order over maps -is not specified and is not guaranteed to be the same from one iteration to the next.</a>” -To keep code from depending on map iteration order, -Go 1.0 started each map iteration at a random index in the map. -A new map implementation introduced in Go 1.1 neglected to randomize -iteration for maps with eight or fewer entries, although the iteration order -can still vary from system to system. -This has allowed people to write Go 1.1 and Go 1.2 programs that -depend on small map iteration order and therefore only work reliably on certain systems. -Go 1.3 reintroduces random iteration for small maps in order to flush out these bugs. -</p> - -<p> -<em>Updating</em>: If code assumes a fixed iteration order for small maps, -it will break and must be rewritten not to make that assumption. -Because only small maps are affected, the problem arises most often in tests. -</p> - -<h3 id="liblink">The linker</h3> - -<p> -As part of the general <a href="//golang.org/s/go13linker">overhaul</a> to -the Go linker, the compilers and linkers have been refactored. -The linker is still a C program, but now the instruction selection phase that -was part of the linker has been moved to the compiler through the creation of a new -library called <code>liblink</code>. -By doing instruction selection only once, when the package is first compiled, -this can speed up compilation of large projects significantly. -</p> - -<p> -<em>Updating</em>: Although this is a major internal change, it should have no -effect on programs. -</p> - -<h3 id="gccgo">Status of gccgo</h3> - -<p> -GCC release 4.9 will contain the Go 1.2 (not 1.3) version of gccgo. -The release schedules for the GCC and Go projects do not coincide, -which means that 1.3 will be available in the development branch but -that the next GCC release, 4.10, will likely have the Go 1.4 version of gccgo. -</p> - -<h3 id="gocmd">Changes to the go command</h3> - -<p> -The <a href="/cmd/go/"><code>cmd/go</code></a> command has several new -features. -The <a href="/cmd/go/"><code>go run</code></a> and -<a href="/cmd/go/"><code>go test</code></a> subcommands -support a new <code>-exec</code> option to specify an alternate -way to run the resulting binary. -Its immediate purpose is to support NaCl. -</p> - -<p> -The test coverage support of the <a href="/cmd/go/"><code>go test</code></a> -subcommand now automatically sets the coverage mode to <code>-atomic</code> -when the race detector is enabled, to eliminate false reports about unsafe -access to coverage counters. -</p> - -<p> -The <a href="/cmd/go/"><code>go test</code></a> subcommand -now always builds the package, even if it has no test files. -Previously, it would do nothing if no test files were present. -</p> - -<p> -The <a href="/cmd/go/"><code>go build</code></a> subcommand -supports a new <code>-i</code> option to install dependencies -of the specified target, but not the target itself. -</p> - -<p> -Cross compiling with <a href="/cmd/cgo/"><code>cgo</code></a> enabled -is now supported. -The CC_FOR_TARGET and CXX_FOR_TARGET environment -variables are used when running all.bash to specify the cross compilers -for C and C++ code, respectively. -</p> - -<p> -Finally, the go command now supports packages that import Objective-C -files (suffixed <code>.m</code>) through cgo. -</p> - -<h3 id="cgo">Changes to cgo</h3> - -<p> -The <a href="/cmd/cgo/"><code>cmd/cgo</code></a> command, -which processes <code>import "C"</code> declarations in Go packages, -has corrected a serious bug that may cause some packages to stop compiling. -Previously, all pointers to incomplete struct types translated to the Go type <code>*[0]byte</code>, -with the effect that the Go compiler could not diagnose passing one kind of struct pointer -to a function expecting another. -Go 1.3 corrects this mistake by translating each different -incomplete struct to a different named type. -</p> - -<p> -Given the C declaration <code>typedef struct S T</code> for an incomplete <code>struct S</code>, -some Go code used this bug to refer to the types <code>C.struct_S</code> and <code>C.T</code> interchangeably. -Cgo now explicitly allows this use, even for completed struct types. -However, some Go code also used this bug to pass (for example) a <code>*C.FILE</code> -from one package to another. -This is not legal and no longer works: in general Go packages -should avoid exposing C types and names in their APIs. -</p> - -<p> -<em>Updating</em>: Code confusing pointers to incomplete types or -passing them across package boundaries will no longer compile -and must be rewritten. -If the conversion is correct and must be preserved, -use an explicit conversion via <a href="/pkg/unsafe/#Pointer"><code>unsafe.Pointer</code></a>. -</p> - -<h3 id="swig">SWIG 3.0 required for programs that use SWIG</h3> - -<p> -For Go programs that use SWIG, SWIG version 3.0 is now required. -The <a href="/cmd/go"><code>cmd/go</code></a> command will now link the -SWIG generated object files directly into the binary, rather than -building and linking with a shared library. -</p> - -<h3 id="gc_flag">Command-line flag parsing</h3> - -<p> -In the gc toolchain, the assemblers now use the -same command-line flag parsing rules as the Go flag package, a departure -from the traditional Unix flag parsing. -This may affect scripts that invoke the tool directly. -For example, -<code>go tool 6a -SDfoo</code> must now be written -<code>go tool 6a -S -D foo</code>. -(The same change was made to the compilers and linkers in <a href="/doc/go1.1#gc_flag">Go 1.1</a>.) -</p> - -<h3 id="godoc">Changes to godoc</h3> -<p> -When invoked with the <code>-analysis</code> flag, -<a href="//godoc.org/golang.org/x/tools/cmd/godoc">godoc</a> -now performs sophisticated <a href="/lib/godoc/analysis/help.html">static -analysis</a> of the code it indexes. -The results of analysis are presented in both the source view and the -package documentation view, and include the call graph of each package -and the relationships between -definitions and references, -types and their methods, -interfaces and their implementations, -send and receive operations on channels, -functions and their callers, and -call sites and their callees. -</p> - -<h3 id="misc">Miscellany</h3> - -<p> -The program <code>misc/benchcmp</code> that compares -performance across benchmarking runs has been rewritten. -Once a shell and awk script in the main repository, it is now a Go program in the <code>go.tools</code> repo. -Documentation is <a href="//godoc.org/golang.org/x/tools/cmd/benchcmp">here</a>. -</p> - -<p> -For the few of us that build Go distributions, the tool <code>misc/dist</code> has been -moved and renamed; it now lives in <code>misc/makerelease</code>, still in the main repository. -</p> - -<h2 id="performance">Performance</h2> - -<p> -The performance of Go binaries for this release has improved in many cases due to changes -in the runtime and garbage collection, plus some changes to libraries. -Significant instances include: -</p> - -<ul> - -<li> -The runtime handles defers more efficiently, reducing the memory footprint by about two kilobytes -per goroutine that calls defer. -</li> - -<li> -The garbage collector has been sped up, using a concurrent sweep algorithm, -better parallelization, and larger pages. -The cumulative effect can be a 50-70% reduction in collector pause time. -</li> - -<li> -The race detector (see <a href="/doc/articles/race_detector.html">this guide</a>) -is now about 40% faster. -</li> - -<li> -The regular expression package <a href="/pkg/regexp/"><code>regexp</code></a> -is now significantly faster for certain simple expressions due to the implementation of -a second, one-pass execution engine. -The choice of which engine to use is automatic; -the details are hidden from the user. -</li> - -</ul> - -<p> -Also, the runtime now includes in stack dumps how long a goroutine has been blocked, -which can be useful information when debugging deadlocks or performance issues. -</p> - -<h2 id="library">Changes to the standard library</h2> - -<h3 id="new_packages">New packages</h3> - -<p> -A new package <a href="/pkg/debug/plan9obj/"><code>debug/plan9obj</code></a> was added to the standard library. -It implements access to Plan 9 <a href="https://9p.io/magic/man2html/6/a.out">a.out</a> object files. -</p> - -<h3 id="major_library_changes">Major changes to the library</h3> - -<p> -A previous bug in <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> -made it possible to skip verification in TLS inadvertently. -In Go 1.3, the bug is fixed: one must specify either ServerName or -InsecureSkipVerify, and if ServerName is specified it is enforced. -This may break existing code that incorrectly depended on insecure -behavior. -</p> - -<p> -There is an important new type added to the standard library: <a href="/pkg/sync/#Pool"><code>sync.Pool</code></a>. -It provides an efficient mechanism for implementing certain types of caches whose memory -can be reclaimed automatically by the system. -</p> - -<p> -The <a href="/pkg/testing/"><code>testing</code></a> package's benchmarking helper, -<a href="/pkg/testing/#B"><code>B</code></a>, now has a -<a href="/pkg/testing/#B.RunParallel"><code>RunParallel</code></a> method -to make it easier to run benchmarks that exercise multiple CPUs. -</p> - -<p> -<em>Updating</em>: The crypto/tls fix may break existing code, but such -code was erroneous and should be updated. -</p> - -<h3 id="minor_library_changes">Minor changes to the library</h3> - -<p> -The following list summarizes a number of minor changes to the library, mostly additions. -See the relevant package documentation for more information about each change. -</p> - -<ul> - -<li> In the <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package, -a new <a href="/pkg/crypto/tls/#DialWithDialer"><code>DialWithDialer</code></a> -function lets one establish a TLS connection using an existing dialer, making it easier -to control dial options such as timeouts. -The package also now reports the TLS version used by the connection in the -<a href="/pkg/crypto/tls/#ConnectionState"><code>ConnectionState</code></a> -struct. -</li> - -<li> The <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a> -function of the <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package -now supports parsing (and elsewhere, serialization) of PKCS #10 certificate -signature requests. -</li> - -<li> -The formatted print functions of the <code>fmt</code> package now define <code>%F</code> -as a synonym for <code>%f</code> when printing floating-point values. -</li> - -<li> -The <a href="/pkg/math/big/"><code>math/big</code></a> package's -<a href="/pkg/math/big/#Int"><code>Int</code></a> and -<a href="/pkg/math/big/#Rat"><code>Rat</code></a> types -now implement -<a href="/pkg/encoding/#TextMarshaler"><code>encoding.TextMarshaler</code></a> and -<a href="/pkg/encoding/#TextUnmarshaler"><code>encoding.TextUnmarshaler</code></a>. -</li> - -<li> -The complex power function, <a href="/pkg/math/cmplx/#Pow"><code>Pow</code></a>, -now specifies the behavior when the first argument is zero. -It was undefined before. -The details are in the <a href="/pkg/math/cmplx/#Pow">documentation for the function</a>. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package now exposes the -properties of a TLS connection used to make a client request in the new -<a href="/pkg/net/http/#Response"><code>Response.TLS</code></a> field. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package now -allows setting an optional server error logger -with <a href="/pkg/net/http/#Server"><code>Server.ErrorLog</code></a>. -The default is still that all errors go to stderr. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package now -supports disabling HTTP keep-alive connections on the server -with <a href="/pkg/net/http/#Server.SetKeepAlivesEnabled"><code>Server.SetKeepAlivesEnabled</code></a>. -The default continues to be that the server does keep-alive (reuses -connections for multiple requests) by default. -Only resource-constrained servers or those in the process of graceful -shutdown will want to disable them. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package adds an optional -<a href="/pkg/net/http/#Transport"><code>Transport.TLSHandshakeTimeout</code></a> -setting to cap the amount of time HTTP client requests will wait for -TLS handshakes to complete. -It's now also set by default -on <a href="/pkg/net/http#DefaultTransport"><code>DefaultTransport</code></a>. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package's -<a href="/pkg/net/http/#DefaultTransport"><code>DefaultTransport</code></a>, -used by the HTTP client code, now -enables <a href="http://en.wikipedia.org/wiki/Keepalive#TCP_keepalive">TCP -keep-alives</a> by default. -Other <a href="/pkg/net/http/#Transport"><code>Transport</code></a> -values with a nil <code>Dial</code> field continue to function the same -as before: no TCP keep-alives are used. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package -now enables <a href="http://en.wikipedia.org/wiki/Keepalive#TCP_keepalive">TCP -keep-alives</a> for incoming server requests when -<a href="/pkg/net/http/#ListenAndServe"><code>ListenAndServe</code></a> -or -<a href="/pkg/net/http/#ListenAndServeTLS"><code>ListenAndServeTLS</code></a> -are used. -When a server is started otherwise, TCP keep-alives are not enabled. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package now -provides an -optional <a href="/pkg/net/http/#Server"><code>Server.ConnState</code></a> -callback to hook various phases of a server connection's lifecycle -(see <a href="/pkg/net/http/#ConnState"><code>ConnState</code></a>). -This can be used to implement rate limiting or graceful shutdown. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package's HTTP -client now has an -optional <a href="/pkg/net/http/#Client"><code>Client.Timeout</code></a> -field to specify an end-to-end timeout on requests made using the -client. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package's -<a href="/pkg/net/http/#Request.ParseMultipartForm"><code>Request.ParseMultipartForm</code></a> -method will now return an error if the body's <code>Content-Type</code> -is not <code>multipart/form-data</code>. -Prior to Go 1.3 it would silently fail and return <code>nil</code>. -Code that relies on the previous behavior should be updated. -</li> - -<li> In the <a href="/pkg/net/"><code>net</code></a> package, -the <a href="/pkg/net/#Dialer"><code>Dialer</code></a> struct now -has a <code>KeepAlive</code> option to specify a keep-alive period for the connection. -</li> - -<li> -The <a href="/pkg/net/http/"><code>net/http</code></a> package's -<a href="/pkg/net/http/#Transport"><code>Transport</code></a> -now closes <a href="/pkg/net/http/#Request"><code>Request.Body</code></a> -consistently, even on error. -</li> - -<li> -The <a href="/pkg/os/exec/"><code>os/exec</code></a> package now implements -what the documentation has always said with regard to relative paths for the binary. -In particular, it only calls <a href="/pkg/os/exec/#LookPath"><code>LookPath</code></a> -when the binary's file name contains no path separators. -</li> - -<li> -The <a href="/pkg/reflect/#Value.SetMapIndex"><code>SetMapIndex</code></a> -function in the <a href="/pkg/reflect/"><code>reflect</code></a> package -no longer panics when deleting from a <code>nil</code> map. -</li> - -<li> -If the main goroutine calls -<a href="/pkg/runtime/#Goexit"><code>runtime.Goexit</code></a> -and all other goroutines finish execution, the program now always crashes, -reporting a detected deadlock. -Earlier versions of Go handled this situation inconsistently: most instances -were reported as deadlocks, but some trivial cases exited cleanly instead. -</li> - -<li> -The runtime/debug package now has a new function -<a href="/pkg/runtime/debug/#WriteHeapDump"><code>debug.WriteHeapDump</code></a> -that writes out a description of the heap. -</li> - -<li> -The <a href="/pkg/strconv/#CanBackquote"><code>CanBackquote</code></a> -function in the <a href="/pkg/strconv/"><code>strconv</code></a> package -now considers the <code>DEL</code> character, <code>U+007F</code>, to be -non-printing. -</li> - -<li> -The <a href="/pkg/syscall/"><code>syscall</code></a> package now provides -<a href="/pkg/syscall/#SendmsgN"><code>SendmsgN</code></a> -as an alternate version of -<a href="/pkg/syscall/#Sendmsg"><code>Sendmsg</code></a> -that returns the number of bytes written. -</li> - -<li> -On Windows, the <a href="/pkg/syscall/"><code>syscall</code></a> package now -supports the cdecl calling convention through the addition of a new function -<a href="/pkg/syscall/#NewCallbackCDecl"><code>NewCallbackCDecl</code></a> -alongside the existing function -<a href="/pkg/syscall/#NewCallback"><code>NewCallback</code></a>. -</li> - -<li> -The <a href="/pkg/testing/"><code>testing</code></a> package now -diagnoses tests that call <code>panic(nil)</code>, which are almost always erroneous. -Also, tests now write profiles (if invoked with profiling flags) even on failure. -</li> - -<li> -The <a href="/pkg/unicode/"><code>unicode</code></a> package and associated -support throughout the system has been upgraded from -Unicode 6.2.0 to <a href="http://www.unicode.org/versions/Unicode6.3.0/">Unicode 6.3.0</a>. -</li> - -</ul> |