When the signal sent for AsyncGetCallTrace or JFR would land on a runtime stub
(like arraycopy), a vtable stub, or the prolog of a compiled method, it
wouldn't be able to detect the sender (caller) frame for multiple reasons. This
patch fixes these cases through adding CodeBlob-specific frame parser which are
in the best position to know how a frame is setup.
The following examples have been profiled with honest-profiler which uses
`AsyncGetCallTrace`.
# `Prof1`
public class Prof1 {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 1000000; i++) {
sb.append("ab");
sb.delete(0, 1);
}
System.out.println(sb.length());
}
}
- Baseline:
Flat Profile (by method):
(t 99.4,s 99.4) AGCT::Unknown Java[ERR=-5]
(t 0.5,s 0.2) Prof1::main
(t 0.2,s 0.2) java.lang.AbstractStringBuilder::append
(t 0.1,s 0.1) AGCT::Unknown not Java[ERR=-3]
(t 0.0,s 0.0) java.lang.AbstractStringBuilder::ensureCapacityInternal
(t 0.0,s 0.0) java.lang.AbstractStringBuilder::shift
(t 0.0,s 0.0) java.lang.String::getBytes
(t 0.0,s 0.0) java.lang.AbstractStringBuilder::putStringAt
(t 0.0,s 0.0) java.lang.StringBuilder::delete
(t 0.2,s 0.0) java.lang.StringBuilder::append
(t 0.0,s 0.0) java.lang.AbstractStringBuilder::delete
(t 0.0,s 0.0) java.lang.AbstractStringBuilder::putStringAt
- With `StubRoutinesBlob::FrameParser`:
Flat Profile (by method):
(t 98.7,s 98.7) java.lang.AbstractStringBuilder::ensureCapacityInternal
(t 0.9,s 0.9) java.lang.AbstractStringBuilder::delete
(t 99.8,s 0.2) Prof1::main
(t 0.1,s 0.1) AGCT::Unknown not Java[ERR=-3]
(t 0.0,s 0.0) AGCT::Unknown Java[ERR=-5]
(t 98.8,s 0.0) java.lang.AbstractStringBuilder::append
(t 98.8,s 0.0) java.lang.StringBuilder::append
(t 0.9,s 0.0) java.lang.StringBuilder::delete
# `Prof2`
import java.util.function.Supplier;
public class Prof2 {
public static void main(String[] args) {
var rand = new java.util.Random(0);
Supplier[] suppliers = {
() -> 0,
() -> 1,
() -> 2,
() -> 3,
};
long sum = 0;
for (int i = 0; i >= 0; i++) {
sum += (int)suppliers[i % suppliers.length].get();
}
}
}
- Baseline:
Flat Profile (by method):
(t 60.7,s 60.7) AGCT::Unknown Java[ERR=-5]
(t 39.2,s 35.2) Prof2::main
(t 1.4,s 1.4) Prof2::lambda$main$3
(t 1.0,s 1.0) Prof2::lambda$main$2
(t 0.9,s 0.9) Prof2::lambda$main$1
(t 0.7,s 0.7) Prof2::lambda$main$0
(t 0.1,s 0.1) AGCT::Unknown not Java[ERR=-3]
(t 0.0,s 0.0) java.lang.Thread::exit
(t 0.9,s 0.0) Prof2$$Lambda$2.0x0000000800c00c28::get
(t 1.0,s 0.0) Prof2$$Lambda$3.0x0000000800c01000::get
(t 1.4,s 0.0) Prof2$$Lambda$4.0x0000000800c01220::get
(t 0.7,s 0.0) Prof2$$Lambda$1.0x0000000800c00a08::get
- With `VtableBlob::FrameParser` and `nmethod::FrameParser`:
Flat Profile (by method):
(t 74.1,s 70.3) Prof2::main
(t 6.5,s 5.5) Prof2$$Lambda$29.0x0000000800081220::get
(t 6.6,s 5.4) Prof2$$Lambda$28.0x0000000800081000::get
(t 5.7,s 5.0) Prof2$$Lambda$26.0x0000000800080a08::get
(t 5.9,s 5.0) Prof2$$Lambda$27.0x0000000800080c28::get
(t 4.9,s 4.9) AGCT::Unknown Java[ERR=-5]
(t 1.2,s 1.2) Prof2::lambda$main$2
(t 0.9,s 0.9) Prof2::lambda$main$3
(t 0.9,s 0.9) Prof2::lambda$main$1
(t 0.7,s 0.7) Prof2::lambda$main$0
(t 0.1,s 0.1) AGCT::Unknown not Java[ERR=-3]
-------------
Commit messages:
- Disable checks in FrameParser when known to be safe
- Allow AsyncGetCallTrace and JFR to unwind stack from vtable stub
- Allow AsyncGetCallTrace and JFR to unwind stack from nmethod's prolog
- JDK-8267985: Allow AsyncGetCallTrace and JFR to walk a stub frame
- 8268178: Extract sender frame parsing to CodeBlock::FrameParser
Changes: https://git.openjdk.java.net/jdk/pull/4436/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4436&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8178287
Stats: 1303 lines in 26 files changed: 1057 ins; 166 del; 80 mod
Patch: https://git.openjdk.java.net/jdk/pull/4436.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/4436/head:pull/4436
PR: https://git.openjdk.java.net/jdk/pull/4436
