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8292351: tty should always live

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Reviewed-by: clanger, coleenp, dholmes
This commit is contained in:
Thomas Stuefe 2022-08-23 05:05:15 +00:00
parent 4da1745836
commit a85a72341b
2 changed files with 34 additions and 7 deletions
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28
src/hotspot/share/utilities/ostream.cpp
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@ -421,8 +421,19 @@ stringStream::~stringStream() {
}
}
// tty needs to be always accessible since there are code paths that may write to it
// outside of the VM lifespan.
// Examples for pre-VM-init accesses: Early NMT init, Early UL init
// Examples for post-VM-exit accesses: many, e.g. NMT C-heap bounds checker, signal handling, AGCT, ...
// During lifetime tty is served by an instance of defaultStream. That instance's deletion cannot
// be (easily) postponed or omitted since it has ties to the JVM infrastructure.
// The policy followed here is a compromise reached during review of JDK-8292351:
// - pre-init: we silently swallow all output. We won't see anything, but at least won't crash
// - post-exit: we write to a simple fdStream, but somewhat mimic the behavior of the real defaultStream
static nullStream tty_preinit_stream;
outputStream* tty = &tty_preinit_stream;
xmlStream* xtty;
outputStream* tty;
extern Mutex* tty_lock;
#define EXTRACHARLEN 32
@ -615,6 +626,9 @@ void fileStream::flush() {
}
}
fdStream fdStream::_stdout_stream(1);
fdStream fdStream::_stderr_stream(2);
void fdStream::write(const char* s, size_t len) {
if (_fd != -1) {
// Make an unused local variable to avoid warning from gcc compiler.
@ -961,13 +975,13 @@ void ostream_exit() {
if (ostream_exit_called) return;
ostream_exit_called = true;
ClassListWriter::delete_classlist();
if (tty != defaultStream::instance) {
delete tty;
// Make sure tty works after VM exit by assigning an always-on functioning fdStream.
outputStream* tmp = tty;
tty = DisplayVMOutputToStderr ? fdStream::stdout_stream() : fdStream::stderr_stream();
if (tmp != &tty_preinit_stream && tmp != defaultStream::instance) {
delete tmp;
}
if (defaultStream::instance != NULL) {
delete defaultStream::instance;
}
tty = NULL;
delete defaultStream::instance;
xtty = NULL;
defaultStream::instance = NULL;
}

13
src/hotspot/share/utilities/ostream.hpp
View File

@ -248,6 +248,8 @@ class fileStream : public outputStream {
class fdStream : public outputStream {
protected:
int _fd;
static fdStream _stdout_stream;
static fdStream _stderr_stream;
public:
fdStream(int fd = -1) : _fd(fd) { }
bool is_open() const { return _fd != -1; }
@ -255,6 +257,17 @@ class fdStream : public outputStream {
int fd() const { return _fd; }
virtual void write(const char* c, size_t len);
void flush() {};
// predefined streams for unbuffered IO to stdout, stderr
static fdStream* stdout_stream() { return &_stdout_stream; }
static fdStream* stderr_stream() { return &_stderr_stream; }
};
// A /dev/null equivalent stream
class nullStream : public outputStream {
public:
void write(const char* c, size_t len) {}
void flush() {};
};
void ostream_init();