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Signals used by the JVM
The types of signals are Exceptions, Errors, Interrupts, and Controls.
Table 1 shows the signals that are used
by the JVM. The signals are grouped in the table by type or use, as
follows:
- Exceptions
- The operating system synchronously raises an appropriate exception signal whenever an unrecoverable condition occurs.
- Errors
- The JVM raises a SIGABRT if it detects a condition from which it cannot recover.
- Interrupts
- Interrupt signals are raised asynchronously, from outside a JVM process, to request shut down.
- Controls
- Other signals that are used by the JVM for control purposes.
| Signal Name | Signal type | Description | Disabled by -Xrs | Disabled by -Xrs:sync |
|---|---|---|---|---|
| SIGBUS (7) | Exception | Incorrect access to memory (data misalignment) | Yes | Yes |
| SIGSEGV (11) | Exception | Incorrect access to memory (write to inaccessible memory) | Yes | Yes |
| SIGILL (4) | Exception | Illegal instruction (attempt to call an unknown machine instruction) | Yes | Yes |
| SIGFPE (8) | Exception | Floating point exception (divide by zero) | Yes | Yes |
| SIGABRT (6) | Error | Abnormal termination. The JVM raises this signal whenever it detects a JVM fault. | Yes | Yes |
| SIGINT (2) | Interrupt | Interactive attention (CTRL-C). JVM exits normally. | Yes | No |
| SIGTERM (15) | Interrupt | Termination request. JVM will exit normally. | Yes | No |
| SIGHUP (1) | Interrupt | Hang up. JVM exits normally. | Yes | No |
| SIGQUIT (3) | Control | A quit signal for a terminal. By default, this triggers a Javadump. | Yes | No |
| SIGTRAP (5) | Control | Used by the JIT. | Yes | Yes |
| SIGRTMIN (32) | Control | Used by the JVM for internal control purposes. | No | No |
| SIGRTMAX (64) | Control | Used by the SDK. | No | No |
| SIGCHLD (17) | Control | Used by the SDK for internal control. | No | No |
Note: A number supplied after the signal name is the standard
numeric value for that signal.
Use the -Xrs (reduce signal usage)
option to prevent the JVM from handling most signals. For more information,
see 
Oracle's Java™ application
launcher page.
Signals 1 (SIGHUP), 2 (SIGINT), 4 (SIGILL), 7 (SIGBUS), 8 (SIGFPE), 11 (SIGSEGV), and 15 (SIGTERM) on JVM threads cause the JVM to shut down; therefore, an application signal handler should not attempt to recover from these unless it no longer requires the JVM.