Add Zygote.startChildZygote() to fork a new process that itself is a zygote.
This adds a new --start-child-zygote argument that instructs the main
zygote to create a new child process that will also be a zygote. The
system_server generates a random name in the abstract socket namespace
for it and the child-zygote to communicate over, and that is passed as
an argument to the new process.
A child-zygote bypasses the normal post-fork-child of the zygote process
in order to preserve itself as a zygote. This means not starting the
Binder threadpool nor launching into ActivityThread. Instead, a
child-zygote calls into its own main function. The main function runs a
ZygoteServer select loop, listening on the socket name specified by the
system_server when it was forked.
Unlike the system zygotes, a child-zygote can be killed without bringing
down the system. Killing a child-zygote will not terminate its child
processes, which will be reparented to init for reaping when they
eventually exit.
Bug: 63749735
Test: m (with multi-project commits landed)
Change-Id: I3e7ebbdba498f8fec1d84cdf927dc43a92be4b68
diff --git a/core/java/com/android/internal/os/Zygote.java b/core/java/com/android/internal/os/Zygote.java
index 89d63f6..e23cbf8 100644
--- a/core/java/com/android/internal/os/Zygote.java
+++ b/core/java/com/android/internal/os/Zygote.java
@@ -71,6 +71,13 @@
private static final ZygoteHooks VM_HOOKS = new ZygoteHooks();
+ /**
+ * An extraArg passed when a zygote process is forking a child-zygote, specifying a name
+ * in the abstract socket namespace. This socket name is what the new child zygote
+ * should listen for connections on.
+ */
+ public static final String CHILD_ZYGOTE_SOCKET_NAME_ARG = "--zygote-socket=";
+
private Zygote() {}
/** Called for some security initialization before any fork. */
@@ -102,6 +109,8 @@
* @param fdsToIgnore null-ok an array of ints, either null or holding
* one or more POSIX file descriptor numbers that are to be ignored
* in the file descriptor table check.
+ * @param startChildZygote if true, the new child process will itself be a
+ * new zygote process.
* @param instructionSet null-ok the instruction set to use.
* @param appDataDir null-ok the data directory of the app.
*
@@ -110,13 +119,13 @@
*/
public static int forkAndSpecialize(int uid, int gid, int[] gids, int runtimeFlags,
int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
- int[] fdsToIgnore, String instructionSet, String appDataDir) {
+ int[] fdsToIgnore, boolean startChildZygote, String instructionSet, String appDataDir) {
VM_HOOKS.preFork();
// Resets nice priority for zygote process.
resetNicePriority();
int pid = nativeForkAndSpecialize(
uid, gid, gids, runtimeFlags, rlimits, mountExternal, seInfo, niceName, fdsToClose,
- fdsToIgnore, instructionSet, appDataDir);
+ fdsToIgnore, startChildZygote, instructionSet, appDataDir);
// Enable tracing as soon as possible for the child process.
if (pid == 0) {
Trace.setTracingEnabled(true, runtimeFlags);
@@ -130,7 +139,7 @@
native private static int nativeForkAndSpecialize(int uid, int gid, int[] gids,int runtimeFlags,
int[][] rlimits, int mountExternal, String seInfo, String niceName, int[] fdsToClose,
- int[] fdsToIgnore, String instructionSet, String appDataDir);
+ int[] fdsToIgnore, boolean startChildZygote, String instructionSet, String appDataDir);
/**
* Called to do any initialization before starting an application.
@@ -190,8 +199,8 @@
native protected static void nativeUnmountStorageOnInit();
private static void callPostForkChildHooks(int runtimeFlags, boolean isSystemServer,
- String instructionSet) {
- VM_HOOKS.postForkChild(runtimeFlags, isSystemServer, instructionSet);
+ boolean isZygote, String instructionSet) {
+ VM_HOOKS.postForkChild(runtimeFlags, isSystemServer, isZygote, instructionSet);
}
/**